Science.gov

Sample records for 2h-chromene ring system

  1. Crystal structure of (7-methyl-2-oxo-2H-chromen-4-yl)methyl piperidine-1-carbo­di­thio­ate

    PubMed Central

    Roopashree, K. R.; Meenakshi, T. G.; Kumar, K. Mahesh; Kotresh, O.; Devarajegowda, H. C.

    2015-01-01

    In the title compound, C17H19NO2S2, the 2H-chromene ring system is nearly planar, with a maximum deviation of 0.0383 (28) Å, and the piperidine ring adopts a chair conformation. The 2H-chromene ring makes dihedral angles of 32.89 (16) and 67.33 (8)°, respectively, with the mean planes of the piperidine ring and the carbodi­thio­ate group. In the crystal, C—H⋯O and weak C—H⋯S hydrogen bonds link the mol­ecules into chains along [001]. The crystal structure also features C—H⋯π and π–π inter­actions, with a centroid–centroid distance of 3.7097 (17) Å. PMID:26396821

  2. Synthesis and properties of 3-nitro-2H-chromenes

    NASA Astrophysics Data System (ADS)

    Korotaev, V. Yu; Sosnovskikh, V. Ya; Barkov, A. Yu

    2013-12-01

    Methods of synthesis and chemical properties of 3-nitro-2H-chromenes, including reactions with nucleophiles, cycloaddition, oxidation and reduction, have been reviewed. Enantioselective reactions involving 3-nitro-2H-chromenes, as well as the stereochemistry of the products, are discussed. The ways of practical use of these compounds are shown. The bibliography includes 115 references.

  3. Ecocatalysis for 2H-chromenes synthesis: an integrated approach for phytomanagement of polluted ecosystems.

    PubMed

    Escande, Vincent; Velati, Alicia; Grison, Claude

    2015-04-01

    A direct, general and efficient method to synthesize 2H-chromenes (2H-benzo[b]pyrans), identified as environmentally friendly pesticides, has been developed. This approach lays on the new concept of ecocatalysis, which involves the use of biomass from phytoextraction processes, as a valuable source of metallic elements for chemical synthesis. This methodology is similar or superior to known methods, affording 2H-chromenes with good to excellent yields (60-98%), including the preparation of precocene I, a natural insect growth regulator, with 91% yield. The approach is ideal for poor reactive substrates such as phenol or naphthol, classically transformed into 2H-chromenes by methodologies associated with environmental issues. These results illustrate the interest of combining phytoextraction and green synthesis of natural insecticides.

  4. Crystal structure of 3-(2,2-di­bromo­acet­yl)-4-hy­droxy-2H-chromen-2-one

    PubMed Central

    Brahmia, Ameni; Ghouili, Afef; Ben Hassen, Rached

    2015-01-01

    The title compound, C11H6Br2O4, is a new coumarin derivative obtained from the reaction of 3-acetyl-4-hy­droxy-2H-chromen-2-one with bromine in acetic acid. The hy­droxyl group in involved in an intra­molecular O—H⋯O hydrogen bond. In the crystal, π–π inter­actions between the rings of the bicycle [inter­centroid distances = 3.498 (2) and 3.539 (2) Å] pack mol­ecules into stacks along the b axis, and weak inter­molecular C—H⋯O hydrogen bonds further link these stacks into layers parallel to the ab plane. PMID:25878797

  5. 3-Phenylalkyl-2H-chromenes and -chromans as novel rhinovirus infection inhibitors.

    PubMed

    Conti, Cinzia; Proietti Monaco, Luca; Desideri, Nicoletta

    2017-02-10

    Following our studies on structure-activity relationships of anti-rhinovirus chromene and chroman derivatives, we designed and synthesized new series of 3-phenylalkyl-2H-chromenes and -chromans bearing differently sized, aliphatic linker chains between the two cycles. The cytotoxicity and the antiviral activity of the new compounds on human rhinovirus (HRV) serotype 1B and 14 infection were evaluated in HeLa cell cultures. Most of the tested compounds interfered with HRV1B multiplication in the micromolar or submicromolar concentrations while HRV14 was less susceptible. 3-[3-(4-Chlorophenyl)propyl]chroman (9c) was selected for preliminary mechanism of action studies due to its potent activity against both serotypes (IC50 of 0.48μM and 1.36μM towards HRV1B and 14, respectively) coupled with high selectivity (SI=206.18 and 73.26, respectively). Results of time of addition/removal studies suggest that 9c, similarly to related derivatives, behaves as a capsid binder interfering with some early events of the HRV1B infectious cycle.

  6. Crystal structure of (Z)-3-{3-(4-chloro­phen­yl)-2-[(4-chloro­phen­yl)imino]-2,3-di­hydro­thia­zol-4-yl}-2H-chromen-2-one

    PubMed Central

    Kayalvizhi, M.; Vasuki, G.; Kumar, R. Raj; Rao, V. Rajeswar

    2014-01-01

    In the title compound, C24H14Cl2N2O2S, the 2H-chromene ring system is approximately planar, with a maximum deviation of 0.025 (2) Å. The thia­zole ring is almost planar, with an r.m.s. deviation of 0.0022 Å, and makes a dihedral angle of 58.52 (7)° with the chromene ring system. The chromene ring system is inclined at angles of 58.3 (1) and 55.39 (9)° with respect to the two chloro­phenyl rings. The two chloro­phenyl rings show significant deviation from coplanarity, with a dihedral angle between them of 47.69 (8)°. The crystal structure features C—H⋯Cl inter­actions extending in (100) and propagating along the a-axis direction and weak π–π inter­actions [centroid–centroid separation = 3.867 (2) Å]. PMID:25553038

  7. Synthesis of function-oriented 2-phenyl-2H-chromene derivatives using L-pipecolinic acid and substituted guanidine organocatalysts.

    PubMed

    Das, Bhaskar C; Mohapatra, Seetaram; Campbell, Philip D; Nayak, Sabita; Mahalingam, Sakkarapalayam M; Evans, Todd

    2010-05-01

    Organocatalytic domino oxa-Michael/aldol reactions between salicylaldehyde with electron deficient olefins are presented. We screened guanidine, 1,1,3,3-tetramethylguanidine (TMG) and L-pipecolinic acid as organocatalysts for this transformation. 3-Substituted 2-phenyl-2H-chromene derivatives are synthesized with high yields and with poor enantioselectivity (5-17% ee) using L-pipecolinic acid while TMG works well with cinnamaldehyde without using co-catalyst. These 3-substituted-2-phenyl-2H-chromene derivatives are further derivatized to synthesize triazole and biotin-containing chromene derivatives, to facilitate purification of protein targets.

  8. Crystal structure of 2-oxo-2H-chromen-3-yl propano­ate

    PubMed Central

    Ziki, Eric; Yoda, Jules; Djandé, Abdoulaye; Saba, Adama; Kakou-Yao, Rita

    2016-01-01

    In the title compound, C12H10O4, the dihedral angle between the coumarin ring system [maximum deviation = 0.033 (8) Å] and the propionate side chain is 78.48 (8)°. In the crystal, weak C—H⋯O hydrogen bonds generate inversion dimers and and C—H⋯π and π–π inter­actions link the dimers into a three-dimensional network. A quantum chemical calculation is in good agreement with the observed structure. PMID:27840708

  9. Crystal structure of 2-oxo-2H-chromen-3-yl propano-ate.

    PubMed

    Ziki, Eric; Yoda, Jules; Djandé, Abdoulaye; Saba, Adama; Kakou-Yao, Rita

    2016-11-01

    In the title compound, C12H10O4, the dihedral angle between the coumarin ring system [maximum deviation = 0.033 (8) Å] and the propionate side chain is 78.48 (8)°. In the crystal, weak C-H⋯O hydrogen bonds generate inversion dimers and and C-H⋯π and π-π inter-actions link the dimers into a three-dimensional network. A quantum chemical calculation is in good agreement with the observed structure.

  10. Experimental, DFT and molecular docking studies on 2-(2-mercaptophenylimino)-4-methyl-2H-chromen-7-ol

    NASA Astrophysics Data System (ADS)

    Singh, Ashok Kumar; Singh, Ravindra Kumar

    2016-10-01

    A new coumarin derivative 2-(2-mercaptophenylimino)-4-methyl-2H-chromen-7-ol (COMSB) was synthesized and characterized with the help of 1H,13C NMR, FT-IR, FT-Raman and mass spectrometry. All quantum calculations were performed at DFT level of theory using B3LYP functional and 6-31G (d,p) as basis set. The UV-Vis spectrum studied by TD-DFT theory, with a hybrid exchange-correlation functional using Coulomb-attenuating method (CAM-B3LYP) in solvent phase gives similar pattern of bands, at energies and is consistent with that of experimental findings. The detailed analysis of vibrational (IR and Raman) spectra and their assignments has been done by computing Potential Energy Distribution (PED) using Gar2ped. Intra-molecular interactions were analyzed by 'Atoms in molecule' (AIM) approach. Computed first static hyperpolarizability (β0 = 8.583 × 10-30 esu) indicates non-linear optical (NLO) response of the molecule. Molecular docking studies show that the title molecule may act as potential acetylcholine esterase (AChE) inhibitor.

  11. Computational and spectral studies of 6-phenylazo-3-(p-tolyl)-2H-chromen-2-one

    NASA Astrophysics Data System (ADS)

    Manimekalai, A.; Vijayalakshmi, N.

    2015-02-01

    6-Phenylazo-3-(p-tolyl)-2H-chromen-2-one 4 was prepared and characterized by IR, 1H, and 13C NMR spectral studies. The optimized structure of the chromen-2-one 4 was investigated by the Gaussian 03 B3LYP density functional method calculations at 6-31G(d,p) basis set. The gauge-independent atomic orbital (GIAO) 13C and 1H chemical shift calculations for the synthesized chromen-2-one in CDCl3 were also made by the same method. The computed IR frequencies of the chromen-2-one and the corresponding vibrational assignments were analyzed by means of potential energy distribution (PED%) calculation using vibrational energy distribution analysis (VEDA) program. The first order hyperpolarizability (βtot), polarizability (α) and dipole moment (μ) were calculated using 6-311G(d,p) basis set and the nonlinear optical (NLO) properties are also addressed theoretically. Stability of the chromen-2-one 4 molecule has been analyzed by calculating the intramolecular charge transfer using natural bond order (NBO) analysis. The molecular electrostatic potentials, HOMO-LUMO energy gap and geometrical parameters were also computed. Topological properties of the electronic charge density in chromen-2-one 4 were analyzed employing the Bader's Atoms in Molecule (AIM) theory which indicated the presence of intramolecular hydrogen bond in the molecule.

  12. Computational and spectral studies of 6-phenylazo-3-(p-tolyl)-2H-chromen-2-one.

    PubMed

    Manimekalai, A; Vijayalakshmi, N

    2015-02-05

    6-Phenylazo-3-(p-tolyl)-2H-chromen-2-one 4 was prepared and characterized by IR, (1)H, and (13)C NMR spectral studies. The optimized structure of the chromen-2-one 4 was investigated by the Gaussian 03 B3LYP density functional method calculations at 6-31G(d,p) basis set. The gauge-independent atomic orbital (GIAO) (13)C and (1)H chemical shift calculations for the synthesized chromen-2-one in CDCl3 were also made by the same method. The computed IR frequencies of the chromen-2-one and the corresponding vibrational assignments were analyzed by means of potential energy distribution (PED%) calculation using vibrational energy distribution analysis (VEDA) program. The first order hyperpolarizability (βtot), polarizability (α) and dipole moment (μ) were calculated using 6-311G(d,p) basis set and the nonlinear optical (NLO) properties are also addressed theoretically. Stability of the chromen-2-one 4 molecule has been analyzed by calculating the intramolecular charge transfer using natural bond order (NBO) analysis. The molecular electrostatic potentials, HOMO-LUMO energy gap and geometrical parameters were also computed. Topological properties of the electronic charge density in chromen-2-one 4 were analyzed employing the Bader's Atoms in Molecule (AIM) theory which indicated the presence of intramolecular hydrogen bond in the molecule.

  13. Crystal structure of 2-oxo-2H-chromen-3-yl 4-chloro­benzoate and Hirshfeld surface analysis

    PubMed Central

    Ziki, Eric; Sosso, Siaka; Mansilla-Koblavi, Frédérica; Djandé, Abdoulaye; Kakou-Yao, Rita

    2017-01-01

    In the title compound, C16H9ClO4 the dihedral angle between the coumarin ring system [maximum deviation = 0.023 (1) Å] and the benzene ring is 73.95 (8)°. In the crystal, π–π inter­actions link the dimers into a three-dimensional framework. A quantum chemical calculation is in generally good agreement with the observed structure, although the calculated dihedral angle between the ring systems (85.7%) is somewhat larger than the observed value [73.95 (8)°]. Hirshfeld surface analysis has been used to confirm and qu­antify the supra­molecular inter­actions. PMID:28083133

  14. Crystal structure of 2-oxo-2H-chromen-3-yl 4-chloro-benzoate and Hirshfeld surface analysis.

    PubMed

    Ziki, Eric; Sosso, Siaka; Mansilla-Koblavi, Frédérica; Djandé, Abdoulaye; Kakou-Yao, Rita

    2017-01-01

    In the title compound, C16H9ClO4 the dihedral angle between the coumarin ring system [maximum deviation = 0.023 (1) Å] and the benzene ring is 73.95 (8)°. In the crystal, π-π inter-actions link the dimers into a three-dimensional framework. A quantum chemical calculation is in generally good agreement with the observed structure, although the calculated dihedral angle between the ring systems (85.7%) is somewhat larger than the observed value [73.95 (8)°]. Hirshfeld surface analysis has been used to confirm and qu-antify the supra-molecular inter-actions.

  15. Enantioselective cascade Michael addition/cyclization reactions of 3-nitro-2H-chromenes with 3-isothiocyanato oxindoles: efficient synthesis of functionalized polycyclic spirooxindoles.

    PubMed

    Tan, Fen; Lu, Liang-Qiu; Yang, Qing-Qing; Guo, Wei; Bian, Qiao; Chen, Jia-Rong; Xiao, Wen-Jing

    2014-03-17

    An unprecedented Zn(OTf)2-catalyzed asymmetric Michael addition/cyclization cascade of 3-nitro-2H-chromenes with 3-isothiocyanato oxindoles has been disclosed. This transformation provides an efficient access to various synthetically important polycyclic spirooxindoles in a highly stereoselective manner under mild conditions (72–99% yields, up to >95:5 d.r. and >99% ee). The reaction leads to the formation of three consecutive stereocenters, including 1,3-nonadjacent tetrasubstituted carbon stereocenters, in a single operation. A bifunctional activation model of the chiral Zn(OTf)2/bis(oxazoline) complex was proposed based on control experiments, wherein the ZnII moiety serves as a Lewis acid and the N atom of the free NH group acts as a Lewis base by a hydrogen-bonding interaction.

  16. Molecular structure, spectroscopic properties and quantum chemical calculations of 8-t-buthyl-4-methyl-2H-chromen-2-one

    NASA Astrophysics Data System (ADS)

    Koparir, Pelin; Sarac, Kamiran; Orek, Cahit; Koparir, Metin

    2016-11-01

    This study acquaints the 8-t-buthyl-4-methyl-2H-chromen 2-one (II) of by quantum chemical calculations and spectral ways. The molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO) 1H and 13C NMR chemical shift values of II in the ground state have been calculated utilizing the density functional method (B3LYP) with the 6-31G(d) basis set. The theoretical vibrational frequencies and chemical shift values display well agreement with experimental values. On the other hand, DFT calculations of molecular electrostatic potentials and frontier molecular orbitals of II were implemented at the B3LYP/6-31G(d) level of theory.

  17. Crystal structure of 1-(8-meth-oxy-2H-chromen-3-yl)ethanone.

    PubMed

    Koh, Dongsoo

    2014-09-01

    In the structure of the title compound, C12H12O3, the di-hydro-pyran ring is fused with the benzene ring. The di-hydro-pyran ring is in a half-chair conformation, with the ring O and methyl-ene C atoms positioned 1.367 (3) and 1.504 (4) Å, respectively, on either side of the mean plane formed by the other four atoms. The meth-oxy group is coplanar with the benzene ring to which it is connected [Cb-Cb-Om-Cm torsion angle = -0.2 (4)°; b = benzene and m = meth-oxy], and similarly the aldehyde is coplanar with respect to the double bond of the di-hydro-pyran ring [Cdh-Cdh-Ca-Oa = -178.1 (3)°; dh = di-hydro-pyran and a = aldehyde]. In the crystal, mol-ecules are linked by weak meth-yl-meth-oxy C-H⋯O hydrogen bonds into supra-molecular chains along the a-axis direction.

  18. Crystal structure of 4-meth­oxy­phenyl 2-oxo-2H-chromene-3-carboxyl­ate

    PubMed Central

    Devarajegowda, H.C.; Suchetan, P. A.; Sreenivasa, S.; Srinivasa, H. T.; Palakshamurthy, B. S.

    2015-01-01

    In the title compound, C17H12O5, the dihedral angle between the planes of the coumarin ring system (r.m.s. deviation = 0.015 Å) and the benzene ring is 48.04 (10)°. The central CO2 group subtends a dihedral angle of 27.15 (11)° with the coumarin ring system and 74.86 (13)° with the benzene ring. In the crystal, mol­ecules are linked by C—H⋯O inter­actions, which generate a three-dimensional network. Very weak C—H⋯π inter­actions are also observed. PMID:26090173

  19. Synthesis Characterization and Biological Activities of Coordination Compounds of 4-Hydroxy-3-nitro-2H-chromen-2-one and Its Aminoethanoic Acid and Pyrrolidine-2-carboxylic Acid Mixed Ligand Complexes

    PubMed Central

    Akinkunmi, Ezekiel; Obuotor, Efere; Olawuni, Idowu; Isabirye, David; Jordaan, Johan

    2017-01-01

    Coordination compounds of 4-hydroxy-3-nitro-2H-chromen-2-one and their mixed ligand complexes with aminoethanoic acid and pyrrolidine-2-carboxylic acid were synthesized by the reaction of Cu(II) and Zn(II) salts in molar ratio 1 : 2 for the coumarin complexes and 1 : 1 : 1 for the mixed ligand complexes, in basic media. The compounds formed were characterized using infrared, Uv-vis spectrophotometric analyses, mass spectrometry, magnetic susceptibility measurements, and EDX analyses. It was concluded that 4-hydroxy-3-nitro-2H-chromen-2-one coordinated as a monobasic ligand for all the complexes; it also coordinated via the carbonyl moiety in the case of the Cu(II) mixed ligand complexes. Similarly it was proposed that the amino acids also coordinated in a bidentate fashion via their amino nitrogen and carboxylate oxygen atoms. The synthesized compounds were screened for their antimicrobial and cytotoxic activities. The complexes exhibited marginal antimicrobial activity but good cytotoxic activity. PMID:28270743

  20. 4-Hy­droxy-3-[(E)-3-phenyl­prop-2-eno­yl]-2H-chromen-2-one

    PubMed Central

    Ghouili, Afef; Ben Hassen, Rached

    2011-01-01

    In the title mol­ecule, C18H12O4, the phenyl ring is twisted by 23.2 (1)° from the mean plane of the chromene system. In the crystal, weak inter­molecular C—H⋯O hydrogen bonds link mol­ecules into zigzag chains extending in the [010] direction. An intra­molecular O—H⋯O hydrogen bond is also present. PMID:22091215

  1. 6-Methyl-2-oxo-N-(quinolin-6-yl)-2H-chromene-3-carboxamide: crystal structure and Hirshfeld surface analysis.

    PubMed

    Gomes, Lígia R; Low, John Nicolson; Fonseca, André; Matos, Maria João; Borges, Fernanda

    2016-08-01

    The title coumarin derivative, C20H14N2O3, displays intra-molecular N-H⋯O and weak C-H⋯O hydrogen bonds, which probably contribute to the approximate planarity of the mol-ecule [dihedral angle between the coumarin and quinoline ring systems = 6.08 (6)°]. The supra-molecular structures feature C-H⋯O hydrogen bonds and π-π inter-actions, as confirmed by Hirshfeld surface analyses.

  2. 6-Methyl-2-oxo-N-(quinolin-6-yl)-2H-chromene-3-carboxamide: crystal structure and Hirshfeld surface analysis

    PubMed Central

    Gomes, Lígia R.; Low, John Nicolson; Fonseca, André; Matos, Maria João; Borges, Fernanda

    2016-01-01

    The title coumarin derivative, C20H14N2O3, displays intra­molecular N—H⋯O and weak C—H⋯O hydrogen bonds, which probably contribute to the approximate planarity of the mol­ecule [dihedral angle between the coumarin and quinoline ring systems = 6.08 (6)°]. The supra­molecular structures feature C—H⋯O hydrogen bonds and π–π inter­actions, as confirmed by Hirshfeld surface analyses. PMID:27536395

  3. Synthesis of new oxadiazole, pyrazole and pyrazolin-5-one bearing 2-((4-methyl-2-oxo-2H-chromen-7-yl)oxy)acetohydrazide analogs as potential antibacterial and antifungal agents.

    PubMed

    Mahesh, M; Bheemaraju, G; Manjunath, G; Venkata Ramana, P

    2016-01-01

    Two series of diversely substituted phenyldiazenyl(2-(4-methyl-2-oxo-2H-chromen-7-yloxy)acetyl)3,5-dimethyl-1H-pyrazole 11a-g and phenyldiazenyl-1-(2-(4-methyl-2-oxo-4-chromen-7-yloxy)acetyl)-3-methyl-1H-pyrazol-5(4)H-one 12a-j were synthesized. All these compounds were characterized by IR, NMR, mass spectra and elemental analyses. The compounds were evaluated for their in vitro antibacterial activity against some Gram-positive bacteria, Staphylococcus aureus, Bacillus subtilis, Gram-negative bacteria, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi and screened for antifungal activity against A. niger, U. maydis. The compounds showed moderate to very good antibacterial activities.

  4. Crystal structure of 7-hy-droxy-8-[(4-methyl-piperazin-1-yl)meth-yl]-2H-chromen-2-one.

    PubMed

    Kubono, Koji; Kise, Ryuma; Kashiwagi, Yukiyasu; Tani, Keita; Yokoi, Kunihiko

    2016-12-01

    In the title compound, C15H18N2O3, the coumarin ring is essentially planar, with an r.m.s. deviation of 0.012 Å. An intra-molecular O-H⋯N hydrogen bond forms an S(6) ring motif. The piperazine ring adopts a chair conformation. In the crystal, a C-H⋯O hydrogen bond generates a C(4) chain motif running along the c axis. The chain structure is stabilized by a C-H⋯π inter-action. The chains are linked by π-π inter-actions [centroid-centroid distance of 3.5745 (11) Å], forming a sheet structure parallel to the bc plane.

  5. Crystal structure of 7-hy­droxy-8-[(4-methyl­piperazin-1-yl)meth­yl]-2H-chromen-2-one

    PubMed Central

    Kubono, Koji; Kise, Ryuma; Kashiwagi, Yukiyasu; Tani, Keita; Yokoi, Kunihiko

    2016-01-01

    In the title compound, C15H18N2O3, the coumarin ring is essentially planar, with an r.m.s. deviation of 0.012 Å. An intra­molecular O—H⋯N hydrogen bond forms an S(6) ring motif. The piperazine ring adopts a chair conformation. In the crystal, a C—H⋯O hydrogen bond generates a C(4) chain motif running along the c axis. The chain structure is stabilized by a C—H⋯π inter­action. The chains are linked by π–π inter­actions [centroid–centroid distance of 3.5745 (11) Å], forming a sheet structure parallel to the bc plane. PMID:27980822

  6. Photo- and thermochromic spirans. 16. * 2-oxo-3-phenyl-5,5-dimethylspiro(1,3-oxazolidine-4,2'-(2H) chromenes)

    SciTech Connect

    Luk'yanov, B.S.; Chernysh, Y.E.; Minkin, V.I.; Nivorozhkin, L.E.

    1986-02-01

    New spirans of the 5,5-dimethyl-3-phenyl-2-oxazolidone series that display photochromic properties in alcohol solutions at about-80/sup 0/C were synthesized. The photoinduced forms are characterized by the presence of two long-wave absorption bands at 350-420 nm and 500-650 nm. The /sup 1/H and /sup 13/C NMR spectra were studied. Anisochronicity of the diastereotopic methyl groups of the oxazolidone ring shows up respectively. only in the /sup 13/C NMR spectra.

  7. Effects of the novel compound DK223 ([1E,2E-1,2-Bis(6-methoxy-2H-chromen-3-yl)methylene]hydrazine) on migration and proliferation of human keratinocytes and primary dermal fibroblasts.

    PubMed

    Ho, Manh Tin; Kang, Hyun Sik; Huh, Jung Sik; Kim, Young Mee; Lim, Yoongho; Cho, Moonjae

    2014-07-23

    Wound healing plays an important role in protecting the human body from external infection. Cell migration and proliferation of keratinocytes and dermal fibroblasts are essential for proper wound healing. Recently, several studies have demonstrated that secondary compounds produced in plants could affect skin cells migration and proliferation. In this study, we identified a novel compound DK223 ([1E,2E-1,2-bis(6-methoxy-2H-chromen-3-yl)methylene]hydrazine) that concomitantly induced human keratinocyte migration and dermal fibroblast proliferation. We evaluated the regulation of epithelial and mesenchymal protein markers, such as E-cadherin and Vimentin, in human keratinocytes, as well as extracellular matrix (ECM) secretion and metalloproteinase families in dermal fibroblasts. DK223 upregulated keratinocyte migration and significantly increased the epithelial marker E-cadherin in a time-dependent manner. We also found that reactive oxygen species (ROS) increased significantly in keratinocytes after 2 h of DK223 exposure, returning to normal levels after 24 h, which indicated that DK223 had an early shock effect on ROS production. DK223 also stimulated fibroblast proliferation, and induced significant secretion of ECM proteins, such as collagen I, III, and fibronectin. In dermal fibroblasts, DK223 treatment induced TGF-β1, which is involved in a signaling pathway that mediates proliferation. In conclusion, DK223 simultaneously induced both keratinocyte migration via ROS production and fibroblast proliferation via TGF-β1 induction.

  8. FT-IR and Raman vibrational analysis, B3LYP and M06-2X simulations of 4-bromomethyl-6-tert-butyl-2H-chromen-2-one

    NASA Astrophysics Data System (ADS)

    Sert, Yusuf; Puttaraju, K. B.; Keskinoğlu, Sema; Shivashankar, K.; Ucun, Fatih

    2015-01-01

    In this study, the experimental and theoretical vibrational frequencies of a newly synthesized bacteriostatic and anti-tumor molecule namely, 4-bromomethyl-6-tert-butyl-2H-chromen-2-one have been investigated. The experimental FT-IR (4000-400 cm-1) and Raman spectra (4000-100 cm-1) of the compound in solid phase have been recorded. The theoretical vibrational frequencies and optimized geometric parameters have been calculated using density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr and DFT/M06-2X: highly parametrized, empirical exchange correlation function) with 6-311++G(d, p) basis set by Gaussian 03 software, for the first time. The assignments of the vibrational frequencies have been done by potential energy distribution (PED) analysis using VEDA 4 software. The theoretical optimized geometric parameters and vibrational frequencies have been found to be in good agreement with the corresponding experimental data and results in the literature. In addition, the highest occupied molecular orbital (HOMO) energy, the lowest unoccupied molecular orbital (LUMO) energy and the other related molecular energy values of the compound have been investigated using the same theoretical calculations.

  9. Effects of the Novel Compound DK223 ([1E,2E-1,2-Bis(6-methoxy-2H-chromen-3-yl)methylene]hydrazine) on Migration and Proliferation of Human Keratinocytes and Primary Dermal Fibroblasts

    PubMed Central

    Ho, Manh Tin; Kang, Hyun Sik; Huh, Jung Sik; Kim, Young Mee; Lim, Yoongho; Cho, Moonjae

    2014-01-01

    Wound healing plays an important role in protecting the human body from external infection. Cell migration and proliferation of keratinocytes and dermal fibroblasts are essential for proper wound healing. Recently, several studies have demonstrated that secondary compounds produced in plants could affect skin cells migration and proliferation. In this study, we identified a novel compound DK223 ([1E,2E-1,2-bis(6-methoxy-2H-chromen-3-yl)methylene]hydrazine) that concomitantly induced human keratinocyte migration and dermal fibroblast proliferation. We evaluated the regulation of epithelial and mesenchymal protein markers, such as E-cadherin and Vimentin, in human keratinocytes, as well as extracellular matrix (ECM) secretion and metalloproteinase families in dermal fibroblasts. DK223 upregulated keratinocyte migration and significantly increased the epithelial marker E-cadherin in a time-dependent manner. We also found that reactive oxygen species (ROS) increased significantly in keratinocytes after 2 h of DK223 exposure, returning to normal levels after 24 h, which indicated that DK223 had an early shock effect on ROS production. DK223 also stimulated fibroblast proliferation, and induced significant secretion of ECM proteins, such as collagen I, III, and fibronectin. In dermal fibroblasts, DK223 treatment induced TGF-β1, which is involved in a signaling pathway that mediates proliferation. In conclusion, DK223 simultaneously induced both keratinocyte migration via ROS production and fibroblast proliferation via TGF-β1 induction. PMID:25056546

  10. Precooler Ring Vacuum System

    SciTech Connect

    Moenich, J.

    1980-10-02

    The precooler vacuum system, as proposed by FNAL, is based on a suitable modification of the existing Electron Cooling Ring System. Because of the magnetic cycle of the bending magnets, distributed ion pumping, as exists in the Electron Cooling Ring, is not applicable. Instead, the proposed pumping will be done with commercial appendage ion pumps mounted approximately every two meters around the circumference of the ring. The loss of effective pumping speed and non-uniformity of system pressure with appendage pumps may not be major considerations but the large number required does effect experimental and analytical equipment placement considerations. There is a distributed pumping technique available which: (1) is not affected by the magnetic cycle of the bending magnets; (2) will provide a minimum of four times the hydrogen pumping speed of the proposed appendage ion pumps; (3) will require no power during pumping after the strip is activated; (4) will provide the heat source for bakeout; (5) is easily replaceable; and (6) can be purchased, installed, and operated at a generous economic advantage over the presently proposed ion pumped system. The pumping technique referred to is non-evaporable gettering with ST101 Zr/Al pumping strip. A technical description of this pumping strip is given on Data Sheet 1 and 2 attached to this report.

  11. Saturn's Spectacular Ring System

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    Saturn's beautiful rings have fascinated astronomers since they were first observed by Galileo in 1610. The main rings consist of solid particles mostly in the 1 cm - 10 m range, composed primarily of water ice. The ring disk is exceptionally thin - the typical local thickness of the bright rings is tens of meters, whereas the diameter of the main rings is 250,000 km! The main rings exhibit substantial radial variations "ringlets", many of which are actively maintained via gravitational perturbations from Saturn's moons. Exterior to the main rings lie tenuous dust rings, which have little mass but occupy a very large volume of space. This seminar will emphasize the physics of ring-moon interactions, recent advances in our understanding of various aspects of the rings obtained from observations taken during 1995 when the rings appeared edge-on to the Earth and then to the Sun, and observations in subsequent years from HST.

  12. Rings in the solar system

    SciTech Connect

    Pollack, J.B.; Cuzzi, J.N.

    1981-11-01

    Saturn, Jupiter, and Uranus have rings with different structure and composition. The rings consist of tiny masses in independent orbits. Photographs and data obtained by the Voyager project have aided in the understanding of Saturn's rings. Spokes have been found in B ring and boards, knots, and twist in F ring. Particles on the order of a micrometer in size are believed to occur in F, B, and A rings. The dominant component is water ice. The rings of Uranus are narrow and separated by broad empty regions. The technique used to study them has been stellar occulation. Nothing is known of particle size. The dominant component is believed to be silicates rich in compounds that absorb sunlight. Jupiter's rings consist of 3 main parts: a bright ring, a diffuse disk, and a halo. Use of Pioneer 10 data and other techniques have indicated particle sizes on the order of several micrometers and some at least a centimeter in diameter. The architecture of the ring system results from the interplay of a number of forces. These include gravitational forces due to moons outside the rings and moonlets embedded in them, electromagnetic forces due to the planet's rotating magnetic field, and even the gentle forces exerted by the dilute gaseous medium in which the rings rotate. Each of these forces is discussed. Several alternative explanations of how the rings arose are considered. The primary difference in these hypotheses is the account of the relationship between the ring particles of today and the primordial ring material. (SC)

  13. 4-Hy­droxy-3-[(4-hy­droxy-2-oxo-2H-3-chromen­yl)(3-thien­yl)meth­yl]-2H-chromen-2-one

    PubMed Central

    Asad, Mohammad; Oo, Chuan-Wei; Osman, Hasnah; Rosli, Mohd Mustaqim; Fun, Hoong-Kun

    2011-01-01

    The whole mol­ecule of the title compound, C23H14O6S, is disordered over two sets of sites with refined occupancies of 0.8733 (12):0.1267 (12). The dihedral angle between the mean planes through the chromene ring systems is 56.31 (5) and 55.2 (3)° for the major and minor components, respectively. In both components, a pair of intra­molecular O—H⋯O inter­actions generate rings of S(8) graph-set motif. In the crystal, the mol­ecules are linked by inter­molecular C—H⋯O inter­actions, forming chains along the b axis. The structure is further stabilized by π–π inter­actions with centroid–centroid distances of 3.594 (2) and 3.608 (5) Å. PMID:21754365

  14. Crystal structure of 4-(4b,8a-di­hydro-9H-pyrido[3,4-b]indol-1-yl)-7-methyl-2H-chromen-2-one

    PubMed Central

    Samundeeswari, S.; Kulkarni, Manohar V.; Anil Kumar, G. N.

    2017-01-01

    The title compound, C21H14N2O2, was prepared by Pictet–Spengler cyclization of tryptamine and 4-formyl coumarin. In the mol­ecule, the dihedral angle between the mean planes of the coumarin and β-carboline ring systems is 63.8 (2)°. In the crystal, mol­ecules are linked via N—H⋯N hydrogen bonds, forming chains along the b-axis direction. Within the chains, there are a number of offset π–π inter­actions present [shortest inter­centroid distance = 3.457 (2) Å]. PMID:28083136

  15. Reflex ring laser amplifier system

    DOEpatents

    Summers, Mark A.

    1985-01-01

    A laser pulse is injected into an unstable ring resonator-amplifier structure. Inside this resonator the laser pulse is amplified, spatially filtered and magnified. The laser pulse is recirculated in the resonator, being amplified, filtered and magnified on each pass. The magnification is chosen so that the beam passes through the amplifier in concentric non-overlapping regions similar to a single pass MOPA. After a number of passes around the ring resonator the laser pulse is spatially large enough to exit the ring resonator system by passing around an output mirror.

  16. 4-Hydr­oxy-3-[(2E)-3-(3,4,5-trimethoxy­phen­yl)prop-2-eno­yl]-2H-chromen-2-one

    PubMed Central

    Mechi, Lassaad; Chtiba, Samar; Hamdi, Naceur; Ben Hassen, Rached

    2009-01-01

    A new chalcone of the coumarin, C21H18O7, containing an annulated α-pyrone ring, was obtained by condensation of the borate complex of ac­yl(hydr­oxy)coumarin with trimethoxy­benzaldehyde. The structure exhibits intra­molecular hydrogen bonding between the hydroxyl oxygen and the ketonic oxygen in the coumarin group. The bicyclic coumarin fragment and the benzene ring form a dihedral angle of 17.1 (4)°. The crystal packing involves dimers inter­connected by C—H⋯O hydrogen bonding. PMID:21582916

  17. (E)-3-(4-Chloro­phen­yl)-1-(5-hy­droxy-2,2-dimethyl-2H-chromen-6-yl)prop-2-en-1-one

    PubMed Central

    Tang, Jie; Chen, Jin-ying; Jiang, Ling-qun

    2012-01-01

    There are two independent mol­ecules in the asymmetric unit of the title compound, C20H17ClO3, each having an E configuration about the –C=C– bond. The dihedral angles between the two benzene rings in the two mol­ecules are 7.17 (11) and 9.82 (11)°. In both mol­ecules, the hy­droxy group is involved in an intra­molecular O—H⋯O hydrogen bond. PMID:22346920

  18. Repression of Human Hepatocellular Carcinoma Growth by Regulating Met/EGFR/VEGFR-Akt/NF-κB Pathways with Theanine and Its Derivative, (R)-2-(6,8-Dibromo-2-oxo-2H-chromene-3-carboxamido)-5-(ethylamino)-5-oxopentanoic Ethyl Ester (DTBrC).

    PubMed

    Zhang, Guoying; Li, Zheng; Wan, Xiaochun; Zhang, Ying; Zhu, Rongqin; Liu, Zhenzhen; Ji, Dexin; Zhang, Huarong; Wu, Fei; Tian, Huihui; Liu, Kun; Wu, Benhao

    2016-09-21

    To explore the potential of theanine against cancer, we have studied the anticancer activities of theanine from tea and its semisynthesized derivative, (R)-2-(6,8-dibromo-2-oxo-2H-chromene-3-carboxamido)-5-(ethylamino)-5-oxopentanoic ethyl ester (DTBrC), in in vitro, ex vivo, and in vivo models of human hepatocellular carcinoma (HHC). Theanine and DTBrC displayed inhibitory effects on the growth and migration of HHC cells in vitro, ex vivo, and in vivo. Theanine and DTBrC significantly enhanced the repression of HHC cell growth in combination with anticancer drug pirarubicin. Theanine and DTBrC completely suppressed HGF- and EGF+HGF-induced migration with a reduction of p53 tumor suppressor level and enhanced the p53 protein expression in HHC cells. The Akt and NF-κB knockdown greatly reduced cancer cell migration with a decrease in CD44 expression. DTBrC and theanine significantly repressed the protein expressions in the Met/EGFR/VEGFR-Akt/NF-κB pathways, which might be the mechanism for their biologic effects.

  19. Crystal structure of di­aqua­bis­(7-di­ethyl­amino-3-formyl-2-oxo-2H-chromen-4-olato-κ2 O 3,O 4)zinc(II) dimethyl sulfoxide disolvate

    PubMed Central

    Davis, Aaron B.; Fronczek, Frank R.; Wallace, Karl J.

    2016-01-01

    The structure of the title coordination complex, [Zn(C14H14NO4)2(H2O)2]·2C2H6OS, shows that the ZnII cation adopts an octa­hedral geometry and lies on an inversion center. Two organic ligands occupy the equatorial positions of the coordination sphere, forming a chelate ring motif via the O atom on the formyl group and another O atom of the carbonyl group (a pseudo-β-diketone motif). Two water mol­ecules occupy the remaining coordination sites of the ZnII cation in the axial positions. The water mol­ecules are each hydrogen bonded to a single dimethyl sulfoxide mol­ecule that has been entrapped in the crystal lattice. PMID:27555957

  20. APS storage ring vacuum system

    SciTech Connect

    Niemann, R.C.; Benaroya, R.; Choi, M.; Dortwegt, R.J.; Goeppner, G.A.; Gonczy, J.; Krieger, C.; Howell, J.; Nielsen, R.W.; Roop, B.; Wehrle, R.B.

    1990-01-01

    The Advanced Photon Source synchrotron radiation facility, under construction at the Argonne National Laboratory, incorporates a large ring for the storage of 7 GeV positrons for the generation of photon beams for the facility's experimental program. The Storage Ring's 1104 m circumference is divided into 40 functional sectors. The sectors include vacuum, beam transport, control, acceleration and insertion device components. The vacuum system, which is designed to operate at a pressure of 1 n Torr, consists of 240 connected sections, the majority of which are fabricated from an aluminum alloy extrusion. The sections are equipped with distributed NeG pumping, photon absorbers with lumped pumping, beam position monitors, vacuum diagnostics and valving. The details of the vacuum system design, selected results of the development program and general construction plans are presented. 11 refs., 6 figs., 3 tabs.

  1. Reflex ring laser amplifier system

    DOEpatents

    Summers, M.A.

    1983-08-31

    The invention is a method and apparatus for providing a reflex ring laser system for amplifying an input laser pulse. The invention is particularly useful in laser fusion experiments where efficient production of high-energy and high power laser pulses is required. The invention comprises a large aperture laser amplifier in an unstable ring resonator which includes a combination spatial filter and beam expander having a magnification greater than unity. An input pulse is injected into the resonator, e.g., through an aperture in an input mirror. The injected pulse passes through the amplifier and spatial filter/expander components on each pass around the ring. The unstable resonator is designed to permit only a predetermined number of passes before the amplified pulse exits the resonator. On the first pass through the amplifier, the beam fills only a small central region of the gain medium. On each successive pass, the beam has been expanded to fill the next concentric non-overlapping region of the gain medium.

  2. Recent observations of Jupiter's ring system

    NASA Astrophysics Data System (ADS)

    Showalter, M.; Burns, J.; de Pater, I.; Hamilton, D.; Horanyi, M.

    2003-04-01

    Jupiter's faint, dusty ring system has several distinct components: a thin main ring, an inner, vertically extended halo, and an outer, fainter pair of "gossamer" rings. This ring system illustrates the complex dynamics of dust after it is ejected from the local moons (Metis, Adrastea, Amalthea and Thebe) and/or embedded parent bodies, and then evolves orbitally under solar and electromagnetic perturbations. The ring system has been observed by four spacecraft (Voyagers 1 and 2, Galileo and Cassini), as well as from the Earth by ground-based observatories and the Hubble Space Telescope (HST). While each individual data set has very limited coverage and content, a complete description of the system is now emerging. This paper will provide a systematic overview of the ring system, based on the latest available data and dynamical models. In particular, the period December 2002 through February 2003 is providing a rare opportunity to watch Jupiter sweep through its full range of Earth-based phase angles while remaining nearly edge-on to the Earth. We will discuss the initial results of an observing program using HST in the visual and the Keck Telescope in the infrared. As the rings pass through opposition, the parent bodies surge in brightness while the dust grains do not; this should provide a new means to distinguish the two populations, better revealing their numbers and locations. Variations in halo thickness with wavelength will provide new information about the sizes and dynamics of the dust grains scattered by Jupiter's strong, inner magnetic field. We will also seek out structures near the outer edge of Amalthea's gossamer ring, hinted at in previous data, which illustrate the dynamics of these dust grains immediately after their initial ejection into the ring.

  3. APS storage ring vacuum system performance

    SciTech Connect

    Noonan, J.R.; Gagliano, J.; Goeppner, G.A.

    1997-06-01

    The Advanced Photon Source (APS) storage ring was designed to operated with 7-GeV, 100-mA positron beam with lifetimes > 20 hours. The lifetime is limited by residual gas scattering and Touschek scattering at this time. Photon-stimulated desorption and microwave power in the rf cavities are the main gas loads. Comparison of actual system gas loads and design calculations will be given. In addition, several special features of the storage ring vacuum system will be presented.

  4. Keck Infrared Observations of Jupiter's Ring System

    NASA Astrophysics Data System (ADS)

    de Pater, Imke; Graham, J. R.; Liu, M. C.; Showalter, M. R.; Burns, J. A.; Nicholson, P. D.; Hamilton, D. P.

    1998-09-01

    We imaged the Jovian ring system at a wavelength of 2.27 mu m with the 10-m W.M. Keck telescope in August and October 1997, when the ring plane was almost edge-on. We obtained the first images of the Jovian halo and gossamer ring in back-scattered light, and the best ground-based images to date of Jupiter's main ring. The main ring is radially confined between 1.70 -- 1.82 R_J, with a maximum (after inversion) at 1.79 R_J, in agreement with the Voyager findings (1 R_J=71398 km). The halo extends inwards from the main ring (at 1.71 R_J) down to 1.40 R_J, bounded by the locations of Lorentz resonances. Roughly 50% of the halo's intensity originates from a region within ~ 700 km from the equatorial plane, while the halo is visible up to ~ 10,000 km above and below the plane. Although the vertical extent agrees with Voyager findings, the halo's intensity relative to that of the main ring in the Keck images is much less than in Voyager images, which is attributed to the fact that the halo contains fewer macroscopic particles, which preferentially backscatter visible light. The gossamer ring is found to have two components, with steep dropoffs in brightness at the orbits of Amalthea and Thebe. The first, Amalthea's gossamer ring, is visible between the main ring's periphery and ~ 2.5 R_J; it is relatively uniform in brightness and has a vertical thickness (FWHM) of 0.06 R_J, clearly broader than the FWHM of the main ring (0.045 R_J) and image resolution of 0.6('') =0.025;R_J. The other component, a factor of five fainter than Amalthea's ring and about twice as broad vertically (FWHM ~ 0.12 ; R_J), is seen inwards from 3.11 R_J, i.e., inwards of Thebe's orbit. Additional material still seems present, albeit barely, at larger distances, until ~ 3.6 R_J, near the edge of our images. Our data are consistent with the Galileo results, and suggest the ring material originates at the bounding satellites Thebe, Amalthea, Adrastea and Metis (see abstracts by Burns et al., and

  5. Lectures on algebraic system theory: Linear systems over rings

    NASA Technical Reports Server (NTRS)

    Kamen, E. W.

    1978-01-01

    The presentation centers on four classes of systems that can be treated as linear systems over a ring. These are: (1) discrete-time systems over a ring of scalars such as the integers; (2) continuous-time systems containing time delays; (3) large-scale discrete-time systems; and (4) time-varying discrete-time systems.

  6. Centaur's ring system formation by close encounters

    NASA Astrophysics Data System (ADS)

    De Santana, Thamiris; Winter, Othon

    2016-10-01

    Rupture of small bodies due to close approach to a massive body is a frequent event in the Solar System. Some of these small bodies can just disintegrate completely or suffer a material loss.In this work we study the gravitational interaction between a giant planet and a small body in close encounters in order to simulate the formation of a planetary ring system around a centaur by the partial rupture of the small body.Considering the current Chariklo's body and a disk of particles around it, we simulated the system under close encounters with one of giant planets.Another motivation for the study is also the centaur Chiron, that is a candidate to have a ring system like Chariklo. The characteristics of the encounters are defined by the impact parameter and the velocity at infinity.The results are presented in terms of conditions that could lead to a rupture that could generate a ring like system.

  7. RF SYSTEM FOR THE SNS ACCUMULATOR RING.

    SciTech Connect

    BLASKIEWICZ, M.; BRENNAN, J.M.; BRODOWSKI, J.; DELONG, J.; METH, M.; SMITH, K.; ZALTSMAN, A.

    2001-06-18

    During accumulation the RF beam current in the spallation neutron source ring rises from 0 to 50 amperes. A clean, 250 nanosecond gap is needed for the extraction kicker risetime. Large momentum spread and small peak current are needed to prevent instabilities and stopband related losses. A robust RF system meeting these requirements has been designed.

  8. Chariklo's ring system 1. Structure of the ring system from stellar occultations

    NASA Astrophysics Data System (ADS)

    Berard, Diane; Sicardy, Bruno; Braga-Ribas, Felipe; camargo, julio; Vieira-Martins, Roberto; Assafin, Marcelo; Sickafoose, Amanda A.; Colas, François; Dauvergne, Jean-Luc; Bath, Karl-Ludwig; Maquet, Lucie; Tancredi, Gonzalo; Richichi, Andrea; Puji, Irawati; Ivanov, Valentin; Bradshaw, Jonathan; Broughton, John; Meza, Erick; Ortiz, Jose-Luis; Duffard, Rene; Leiva, Rodrigo

    2016-10-01

    Two dense and narrow rings around Chariklo (the largest centaur object known to date) were discovered by stellar occultation on June 3, 2013 (Braga-Ribas et al., Nature 508, 72, 2014). The main and larger ring is called C1R, while the faintest one is called C2R.Here we report six others occultations by Chariklo's ring system observed on February 16, March 16, April 29, June 28, 2014 and April 26, May 12, 2015. They provide a total of fifteen ring profiles, among which are four resolved profiles of C1R.The latter exhibits a W-shape profile that is essentially opaque at the edges. Its width varies from 4.8 to 7.7 km over the available longitude range. Those caracteristics have been detected in Uranus elliptic rings. The equivalent width We (normal opacity x physical radial width) of C1R is 2 km with typical rms of 1 km, while C2R has We of 0.2 km (rms ~ 0.1 km). None of the rings exhibits variation of We with longitude.Assuming the rings are circular, we can exhibit a pole which is compatible with the two multi-chord ring detections (June 3, 2013 and April 29, 2014): αp=151.4° and δp=41.5°. We will then estimate an upper limit of a possible ring eccentricity based on those two observations.Part of the research leading to these results has received funding from the European Research Council under the European Community's H2020 (2014-2020/ ERC Grant Agreement n 669416 "LUCKY STAR").

  9. Integrability of particle system around a ring source as the Newtonian limit of a black ring

    NASA Astrophysics Data System (ADS)

    Igata, Takahisa; Ishihara, Hideki; Yoshino, Hirotaka

    2015-04-01

    The geodesic equation in the five-dimensional singly rotating black ring is nonintegrable, unlike the case of the Myers-Perry black hole. In the Newtonian limit of the black ring, its geodesic equation agrees with the equation of motion of a particle in the Newtonian potential due to a homogeneous ring gravitational source. In this paper, we show that the Newtonian equation of motion allows the separation of variables in the spheroidal coordinates, providing a nontrivial constant of motion quadratic in momenta. This shows that the Newtonian limit of a black ring recovers the symmetry of its geodesic system, and the geodesic chaos is caused by relativistic effects.

  10. Crystal structures of two hydrazinecarbo-thio-amide derivatives: (E)-N-ethyl-2-[(4-oxo-4H-chromen-3-yl)methyl-idene]hydrazinecarbo-thio-amide hemi-hydrate and (E)-2-[(4-chloro-2H-chromen-3-yl)methyl-idene]-N-phenyl-hydrazinecarbo-thio-amide.

    PubMed

    Gangadharan, Rajeswari; Haribabu, Jebiti; Karvembu, Ramasamy; Sethusankar, K

    2015-03-01

    The title compounds, C13H13N3O2S·0.5H2O, (I), and C17H14ClN3OS, (II), are hydrazinecarbo-thio-amide derivatives. Compound (I) crystallizes with two independent mol-ecules (A and B) and a water mol-ecule of crystallization in the asymmetric unit. The chromene moiety is essentially planar in mol-ecules A and B, with maximum deviations of 0.028 (3) and 0.016 (3) Å, respectively, for the carbonyl C atoms. In (II), the pyran ring of the chromene moiety adopts a screw-boat conformation and the phenyl ring is inclined by 61.18 (9)° to its mean plane. In the crystal of (I), bifurcated N-H⋯O and C-H⋯O hydrogen bonds link the two independent mol-ecules forming A-B dimers with two R 2 (1)(6) ring motifs, and R 2 (2)(10) and R 2 (2)(14) ring motifs. In addition to these, the water mol-ecule forms tetra-furcated hydrogen bonds which alternately generate R 4 (4)(12) and R 6 (6)(22) graph-set ring motifs. There are also π-π [inter-centroid distances = 3.5648 (14) and 3.6825 (15) Å] inter-actions present, leading to the formation of columns along the c-axis direction. In the crystal of (II), mol-ecules are linked by pairs of N-H⋯S hydrogen bonds, forming inversion dimers with an R 2 (2)(8) ring motif. The dimers are linked by C-H⋯π inter-actions, forming ribbons lying parallel to (210).

  11. Cooling system for three hook ring segment

    DOEpatents

    Campbell, Christian X.; Eng, Darryl; Lee, Ching-Pang; Patat, Harry

    2014-08-26

    A triple hook ring segment including forward, midsection and aft mounting hooks for engagement with respective hangers formed on a ring segment carrier for supporting a ring segment panel, and defining a forward high pressure chamber and an aft low pressure chamber on opposing sides of the midsection mounting hook. An isolation plate is provided on the aft side of the midsection mounting hook to form an isolation chamber between the aft low pressure chamber and the ring segment panel. High pressure air is supplied to the forward chamber and flows to the isolation chamber through crossover passages in the midsection hook. The isolation chamber provides convection cooling air to an aft portion of the ring segment panel and enables a reduction of air pressure in the aft low pressure chamber to reduce leakage flow of cooling air from the ring segment.

  12. Keck Observations of Dusty Rings in our Solar System

    NASA Astrophysics Data System (ADS)

    de Pater, Imke

    2007-08-01

    All four giant planets are surrounded by ring systems, which typically consist of a combination of large and small bodies, as well as fine dust. With the 10-m W.M. Keck telescope on Mauna Kea (Hawaii) we have focused on observing the dusty rings of these planets. In this review I will summarize our data sets. I will focus on our most recent results with regard to Jupiter and Uranus, both observed during ring plane crossings. Jupiter's ring system was observed in December 2002 and January 2003 at 2.2 micron, where we used both the facility near-infrared camera NIRC with a pixel size of 0.151" (˜500 km at Jupiter), and the adaptive optics camera NIRC2, with a pixelsize of 0.04" and 0.01". The images were "onion-peeled" to provide radial scans of the rings. We will compare results of the main ring with Galileo data, and comment on similarities and differences with respect to the location of parent material in the ring. The radial structure of the gossamer rings is very different than expected based upon the Burns et al (1999) formation scenarios. The rings are not sheets of material, but narrow rings located just interior to the orbits of Amalthea and Thebe. The Amalthea ring shows a structure analagous to the main ring. Its inner boundary is near the location of synchronous orbit. Radial variations in the Thebe ring suggest "sculpting" by Lorentz resonances. We will present images of Uranus "hot of the press"; we are scheduled to observe in July and August when the rings are edge-on.

  13. Wind turbine ring/shroud drive system

    DOEpatents

    Blakemore, Ralph W.

    2005-10-04

    A wind turbine capable of driving multiple electric generators having a ring or shroud structure for reducing blade root bending moments, hub loads, blade fastener loads and pitch bearing loads. The shroud may further incorporate a ring gear for driving an electric generator. In one embodiment, the electric generator may be cantilevered from the nacelle such that the gear on the generator drive shaft is contacted by the ring gear of the shroud. The shroud also provides protection for the gearing and aids in preventing gear lubricant contamination.

  14. Recent Hubble Observations of Jupiter's Ring System

    NASA Astrophysics Data System (ADS)

    Showalter, M. R.; Burns, J. A.; de Pater, I.; Hamilton, D. P.; Horanyi, M.

    2003-05-01

    The period December 2002 through February 2003 provided a rare opportunity to watch Jupiter sweep through its full range of Earth-based phase angles while the rings remained nearly edge-on to Earth. We used this period for a series of Jovian ring observations using the High Resolution Channel (HRC) of Hubble's new Advanced Camera for Surveys (ACS). Phase angles span 0.17o--10o. Our images showed the main ring, Adrastea and Metis with very high signal-to-noise ratios (SNR). Amalthea's gossamer ring was detected (and vertically resolved) in a small set of specially targeted images. Somewhat surprisingly, we have not yet been able to detect the halo in any of our images, perhaps because it is obscured by the scattered light from Jupiter's disk, positioned just 4'' outside the HRC's field of view. Preliminary results from this data set are as follows. (1) The ring is substantially less red than the moons, suggesting that fine dust represents a significant fraction of its backscattering intensity. (2) Neither the rings nor the embedded moons Metis and Adrastea have significant opposition surges. We were hoping to use the surge, which is characteristic of most macroscopic bodies but not dust, as an indicator of where any embedded ring parent bodies might reside. (3) Because our data are so sensitive to Metis (radius ˜ 20 km) and Adrastea ( ˜ 8 km), we believe that bodies as small as 3--4 km in radius should have been detected in the data. In an initial search, no additional bodies have been detected. (4) The Amalthea ring shows an enhancement in brightness in its outermost 15,000 km. This is consistent with what was seen in Galileo images at very high phase angles. Support for this work was provided by NASA through the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy under NASA contract NAS5-26555.

  15. Ring-laser gyroscope system using dispersive element(s)

    NASA Technical Reports Server (NTRS)

    Smith, David D. (Inventor)

    2010-01-01

    A ring-laser gyroscope system includes a ring-laser gyroscope (RLG) and at least one dispersive element optically coupled to the RLG's ring-shaped optical path. Each dispersive element has a resonant frequency that is approximately equal to the RLG's lasing frequency. A group index of refraction defined collectively by the dispersive element(s) has (i) a real portion that is greater than zero and less than one, and (ii) an imaginary portion that is less than zero.

  16. Superfluid qubit systems with ring shaped optical lattices.

    PubMed

    Amico, Luigi; Aghamalyan, Davit; Auksztol, Filip; Crepaz, Herbert; Dumke, Rainer; Kwek, Leong Chuan

    2014-03-06

    We study an experimentally feasible qubit system employing neutral atomic currents. Our system is based on bosonic cold atoms trapped in ring-shaped optical lattice potentials. The lattice makes the system strictly one dimensional and it provides the infrastructure to realize a tunable ring-ring interaction. Our implementation combines the low decoherence rates of neutral cold atoms systems, overcoming single site addressing, with the robustness of topologically protected solid state Josephson flux qubits. Characteristic fluctuations in the magnetic fields affecting Josephson junction based flux qubits are expected to be minimized employing neutral atoms as flux carriers. By breaking the Galilean invariance we demonstrate how atomic currents through the lattice provide an implementation of a qubit. This is realized either by artificially creating a phase slip in a single ring, or by tunnel coupling of two homogeneous ring lattices. The single qubit infrastructure is experimentally investigated with tailored optical potentials. Indeed, we have experimentally realized scaled ring-lattice potentials that could host, in principle, n ~ 10 of such ring-qubits, arranged in a stack configuration, along the laser beam propagation axis. An experimentally viable scheme of the two-ring-qubit is discussed, as well. Based on our analysis, we provide protocols to initialize, address, and read-out the qubit.

  17. Superfluid qubit systems with ring shaped optical lattices

    PubMed Central

    Amico, Luigi; Aghamalyan, Davit; Auksztol, Filip; Crepaz, Herbert; Dumke, Rainer; Kwek, Leong Chuan

    2014-01-01

    We study an experimentally feasible qubit system employing neutral atomic currents. Our system is based on bosonic cold atoms trapped in ring-shaped optical lattice potentials. The lattice makes the system strictly one dimensional and it provides the infrastructure to realize a tunable ring-ring interaction. Our implementation combines the low decoherence rates of neutral cold atoms systems, overcoming single site addressing, with the robustness of topologically protected solid state Josephson flux qubits. Characteristic fluctuations in the magnetic fields affecting Josephson junction based flux qubits are expected to be minimized employing neutral atoms as flux carriers. By breaking the Galilean invariance we demonstrate how atomic currents through the lattice provide an implementation of a qubit. This is realized either by artificially creating a phase slip in a single ring, or by tunnel coupling of two homogeneous ring lattices. The single qubit infrastructure is experimentally investigated with tailored optical potentials. Indeed, we have experimentally realized scaled ring-lattice potentials that could host, in principle, n ~ 10 of such ring-qubits, arranged in a stack configuration, along the laser beam propagation axis. An experimentally viable scheme of the two-ring-qubit is discussed, as well. Based on our analysis, we provide protocols to initialize, address, and read-out the qubit. PMID:24599096

  18. The Secular Evolution of a Close Ring-Satellite System

    NASA Astrophysics Data System (ADS)

    Hahn, Joseph M.

    2007-10-01

    Current literature on ring-satellite interactions tells us that the long-term orbital stability of a satellite that orbits near a planetary ring is uncertain. This is because the satellite's perturbations at its Lindblad and corotation resonances in the ring tend to alter the satellite's eccentricity e, but it is unclear whether e-damping or e-excitation is the result, since that depends on whether particle motions at the corotation resonances are unsaturated (Goldreich & Tremaine 1982). Further, the stability of the satellite's inclination I seems grim, since the satellite's inclination is excited by its many vertical resonances in the ring (Borderies et al 1984). Consequently, it is unclear whether the small gap-embedded satellites Pan (which inhabits the Encke gap in Saturn's A ring) and Daphnis (which inhabits the Keeler gap) should in fact reside in nearly circular orbits that are coplanar with the ring. To address this uncertainty, the following considers the satellite's secular gravitational perturbations of the ring, which can also alter the satellite's e and I. The Lagrange planetary equations are used to show that a small gap-embedded satellite can launch spiral density and spiral bending waves that propagate radially outwards from the gap's outer edge. These one-armed waves propagate via the secular part of the ring's self-attraction, and they tend to have low amplitudes and long wavelengths, 100's of km in Saturn's A ring. The excitation of these waves also damps the satellite's e and I at rates that depend on the satellite's mass, ring surface density, the gap width, and the planet's oblateness (Hahn 2007). These analytic predictions are also confirmed using the `rings-model' of Hahn (2003) to simulate a ring-satellite system. Whether this secular interaction can stabilize a satellite's e and I will be determined, and whether these low-amplitude waves have any observational consequences will also be discussed.

  19. Numerical experiments in ringing of offshore systems under viscous loads

    SciTech Connect

    Gurley, K.R.; Kareem, A.

    1996-12-31

    A phenomenon which has recently received much attention in offshore engineering is the ringing response of structures. This high frequency transient type response has been observed in nature, particularly in tension leg platforms (TLPs). Given the implications of this behavior on the fatigue life of tendons, it is important that it be considered for response analysis. Significant progress has been made in recent years in identifying the nonlinear mechanisms that induce ringing in complex offshore structural systems. This introductory study-uses a simple model to numerically demonstrates several of the more salient features that are commonly cited in current literature, and shows that viscous loads may result in inducing ringing type response of members under certain conditions. Ringing response in pitch due to viscous loading is simulated on a column piercing the surface, and the significant contributing force mechanisms are identified. System characteristics are altered to ameliorate the performance of these systems.

  20. The Rings Node for the Planetary Data System

    NASA Technical Reports Server (NTRS)

    Showalter, Mark R.; Bollinger, Kenneth J.; Cuzzi, Jeffrey N.; Nicholson, Philip D.

    1994-01-01

    The Planetary Data System's Rings Node is devoted to the archiving and distributing of scientific data sets relevant to planetary ring systems. The two major classes of ring data are images and occultation profiles, although a variety of additional data types (e.g. spectra, particle absorption signatures, etc.) are also of interest. A large fraction of our data sets are from the Voyager missions to the outer planets, but Earth-based and Hubble Space Telescope data sets are also represented. Archiving work often includes re-formatting the data into standardized formats and reconstructing some of the data processing steps. The Rings Node also performs a variety of services to support research into these data sets. These services include developing on-line catalogs and information systems, filling orders for data, developing software tools, and coordinating special observing campaigns.

  1. A ring system detected around the Centaur (10199) Chariklo.

    PubMed

    Braga-Ribas, F; Sicardy, B; Ortiz, J L; Snodgrass, C; Roques, F; Vieira-Martins, R; Camargo, J I B; Assafin, M; Duffard, R; Jehin, E; Pollock, J; Leiva, R; Emilio, M; Machado, D I; Colazo, C; Lellouch, E; Skottfelt, J; Gillon, M; Ligier, N; Maquet, L; Benedetti-Rossi, G; Ramos Gomes, A; Kervella, P; Monteiro, H; Sfair, R; El Moutamid, M; Tancredi, G; Spagnotto, J; Maury, A; Morales, N; Gil-Hutton, R; Roland, S; Ceretta, A; Gu, S-h; Wang, X-b; Harpsøe, K; Rabus, M; Manfroid, J; Opitom, C; Vanzi, L; Mehret, L; Lorenzini, L; Schneiter, E M; Melia, R; Lecacheux, J; Colas, F; Vachier, F; Widemann, T; Almenares, L; Sandness, R G; Char, F; Perez, V; Lemos, P; Martinez, N; Jørgensen, U G; Dominik, M; Roig, F; Reichart, D E; LaCluyze, A P; Haislip, J B; Ivarsen, K M; Moore, J P; Frank, N R; Lambas, D G

    2014-04-03

    Hitherto, rings have been found exclusively around the four giant planets in the Solar System. Rings are natural laboratories in which to study dynamical processes analogous to those that take place during the formation of planetary systems and galaxies. Their presence also tells us about the origin and evolution of the body they encircle. Here we report observations of a multichord stellar occultation that revealed the presence of a ring system around (10199) Chariklo, which is a Centaur--that is, one of a class of small objects orbiting primarily between Jupiter and Neptune--with an equivalent radius of 124 ±  9 kilometres (ref. 2). There are two dense rings, with respective widths of about 7 and 3 kilometres, optical depths of 0.4 and 0.06, and orbital radii of 391 and 405 kilometres. The present orientation of the ring is consistent with an edge-on geometry in 2008, which provides a simple explanation for the dimming of the Chariklo system between 1997 and 2008, and for the gradual disappearance of ice and other absorption features in its spectrum over the same period. This implies that the rings are partly composed of water ice. They may be the remnants of a debris disk, possibly confined by embedded, kilometre-sized satellites.

  2. National Synchrotron Light Source II storage ring vacuum systems

    SciTech Connect

    Hseuh, Hsiao-Chaun; Hetzel, Charles; Leng, Shuwei; Wilson, King; Xu, Huijuan; Zigrosser, Douglas

    2016-04-05

    The National Synchrotron Light Source II, completed in 2014, is a 3-GeV synchrotron radiation (SR) facility at Brookhaven National Laboratory and has been in steady operation since. With a design electron current of 500 mA and subnanometer radians horizontal emittance, this 792-m circumference storage ring is providing the highest flux and brightness x-ray beam for SR users. Also, the majority of the storage ring vacuum chambers are made of extruded aluminium. Chamber sections are interconnected using low-impedance radiofrequency shielded bellows. SR from the bending magnets is intercepted by water-cooled compact photon absorbers resided in the storage ring chambers. Finally, this paper presents the design of the storage ring vacuum system, the fabrication of vacuum chambers and other hardware, the installation, the commissioning, and the continuing beam conditioning of the vacuum systems.

  3. National Synchrotron Light Source II storage ring vacuum systems

    DOE PAGES

    Hseuh, Hsiao-Chaun; Hetzel, Charles; Leng, Shuwei; ...

    2016-04-05

    The National Synchrotron Light Source II, completed in 2014, is a 3-GeV synchrotron radiation (SR) facility at Brookhaven National Laboratory and has been in steady operation since. With a design electron current of 500 mA and subnanometer radians horizontal emittance, this 792-m circumference storage ring is providing the highest flux and brightness x-ray beam for SR users. Also, the majority of the storage ring vacuum chambers are made of extruded aluminium. Chamber sections are interconnected using low-impedance radiofrequency shielded bellows. SR from the bending magnets is intercepted by water-cooled compact photon absorbers resided in the storage ring chambers. Finally, thismore » paper presents the design of the storage ring vacuum system, the fabrication of vacuum chambers and other hardware, the installation, the commissioning, and the continuing beam conditioning of the vacuum systems.« less

  4. Quantized levitation states of superconducting multiple-ring systems

    SciTech Connect

    Haley, S.B.; Fink, H.J.

    1996-02-01

    The quantized levitation, trapped, and suspension states of a magnetic microsphere held in equilibrium by two fixed superconducting (SC) microrings are calculated by minimizing the free energy of the system. Each state is a discrete function of two independent fluxoid quantum numbers of the rings. When the radii of the SC rings are of the same order as the Ginzburg-Landau coherence length {xi}({ital T}), the system exhibits a small set of gravity and temperature-dependent levels. The levels of a weakly magnetized particle are sensitive functions of the gravitational field, indicating potential application as an accelerometer, and for trapping small magnetic particles in outer space or on Earth. The equilibrium states of a SC ring levitated by another SC ring are also calculated. {copyright} {ital 1996 The American Physical Society.}

  5. Progress Report on the g-2 Storage Ring Magnet System

    SciTech Connect

    Bunce, G.A.; Cullen, J.; Danby, G.; Green, M.A.; Jackson, J.; Jia, L.; Krienen, F.; Meier, R.; Meng, W.; Morse, W.; Pai, C.; Polk, I.; Prodell, A.; Shutt, R.; Snydstrup, L.; Yamamoto, A.

    1995-06-01

    The 3.1 GeV muon storage ring for the g-2 experiment at Brookhaven National Laboratory has three large solenoid magnets that form a continuous 1.451 tesla storage ring dipole with an average beam bend radius of 7.1 meters. In addition to the three storage ring solenoids, there is an inflector dipole with nested dipole coils that create very little stray magnetic field. A superconducting shield on the inflector gets rid of most of the remaining stray flux. This paper reports on the progress made on the storage ring solenoid magnet system and the inflector as of June 1995. The results of cryogenic system tests are briefly reported.

  6. The Ring System Discovered Around the Centaur Object (10199) Chariklo

    NASA Astrophysics Data System (ADS)

    Braga-Ribas, F.; Sicardy, B.; Ortiz, J. L.; Vieira Martins, R.; Colas, F.; Duffard, R.; Camargo, J. I. B.; Desmars, J.; Gulbis, A.; Assafin, M.; Maquet, L.; Beisker, W.; Benedetti-Rossi, G.; Vachier, F.; Dumas, C.; Ivanov, V. D.; Renner, S.; Bath, K. L.; Klotz, A.; Pollock, J. T.

    2014-12-01

    Observations of a stellar occultation on 03 June 2013 led to the discovery of the first ring system around a small Solar System object, the Centaur (10199) Chariklo (Braga-Ribas et al. 2014, Nature, 508, 72). The object has a radius of about 125 km and moves on an unstable orbit between Saturn and Uranus, with lifetime of about 10 Myr. The fifth ring system ever discovered (after those around the four giant planets) is made of two dense and narrow rings with respective widths of 7 and 3 kilometers, normal optical depths of 0.4 and 0.06, and orbital radii of 391 and 405 kilometers, respectively (see figure). They are separated by an empty gap of about 9 km (see Figure 1). Their current configuration may be explained by the presence of putative kilometric-sized satellites. By means of the shepherd mechanism, satellites can confine and open the gap between the rings, otherwise they would spread out in few thousand years. From 1997 to 2008, the Chariklo system exhibited an unexplained behavior. It dimmed by 0.6 in absolute magnitude and the water-ice band in its spectrum, formerly observed, could not be detected in 2008. All this is simply explained by the rings' pole orientation, which implies that they were seen edge-on in 2007-2008. We can also calculate their reflectivity I/F ~ 0.1. Spectroscopic and photometric observations of the system allowed us to calculate the amount of water ice and silicate elements in the rings as well as on the main body. No water ice is detectable on the surface of Chariklo. New stellar occultations by the Chariklo system were observed in 2014, and they show the fine structure of the rings as well confirm the preferred pole position from the 2013 event. These findings will be presented and possible formation scenarios will be discussed.

  7. Gravito-electrodynamics and the structure of planetary ring systems

    NASA Technical Reports Server (NTRS)

    Mendis, D. A.

    1984-01-01

    Recent spacecraft observations of the Saturnian and Jovian ring systems have highlighted a plethora of interesting new phenomena associated with those regions containing fine (micron and sub-micron sized) dust. Recognizing that these dust grains, by virtue of being immersed within the planetary magnetospheres, are electrostatically charged to the point that they experience comparable gravitational and electric forces, a new 'gravito-electrodynamic' theory has been developed to describe their dynamics. This theory has been successful in explaining all these phenomena in a systematic way. In this review, the basic model and its range of validity are outlined, and its application to the Saturnian and Jovian ring systems are discussed.

  8. SIMULATION STUDY AND INITIAL TEST OF THESNS RING RF SYSTEM

    SciTech Connect

    Zhang, Yan; Ma, Hengjie; Holmes, Jeffrey A; Champion, Mark; Chu, Paul; Cousineau, Sarah M; Hardek, Thomas W; Plum, Michael A; Danilov, Viatcheslav; Piller, Chip

    2008-01-01

    The rfsimulator code was developed for the study of the Spallation Neutron Source (SNS) dual-harmonic ring RF control. It uses time-domain solvers to compute beam-cavity interactions and FFT methods to simulate the time responses of the linear RF system. The important elements of the system considered in the model include beam loading, dynamic cavity detuning, circuit bandwidth, loop delay, proportional-integral controller for feedback and adaptive feed forward, stochastic noise, width-in-turn loop parameter change, beam current fluctuation, and bunch leakage. As the beam power increases, beam loss in the ring goes up and thus precise control of the bunching RF phase and amplitude is required to limit beam loss. The code will help in the development of a functional RF control and in achieving the goal of minimizing beam loss in the accumulator ring.

  9. Clump detections and limits on moons in Jupiter's ring system.

    PubMed

    Showalter, Mark R; Cheng, Andrew F; Weaver, Harold A; Stern, S Alan; Spencer, John R; Throop, Henry B; Birath, Emma M; Rose, Debi; Moore, Jeffrey M

    2007-10-12

    The dusty jovian ring system must be replenished continuously from embedded source bodies. The New Horizons spacecraft has performed a comprehensive search for kilometer-sized moons within the system, which might have revealed the larger members of this population. No new moons were found, however, indicating a sharp cutoff in the population of jovian bodies smaller than 8-kilometer-radius Adrastea. However, the search revealed two families of clumps in the main ring: one close pair and one cluster of three to five. All orbit within a brighter ringlet just interior to Adrastea. Their properties are very different from those of the few other clumpy rings known; the origin and nonrandom distribution of these features remain unexplained, but resonant confinement by Metis may play a role.

  10. Nonlinear hopping transport in ring systems and open channels.

    PubMed

    Einax, Mario; Körner, Martin; Maass, Philipp; Nitzan, Abraham

    2010-01-21

    We study the nonlinear hopping transport in one-dimensional rings and open channels. Analytical results are derived for the stationary current response to a constant bias without assuming any specific coupling of the rates to the external fields. It is shown that anomalous large effective jump lengths, as observed in recent experiments by taking the ratio of the third-order nonlinear and the linear conductivity, can occur already in ordered systems. Rectification effects due to site energy disorder in ring systems are expected to become irrelevant for large system sizes. In open channels, in contrast, rectification effects occur already for disorder in the jump barriers and do not vanish in the thermodynamic limit. Numerical solutions for a sinusoidal bias show that the ring system provides a good description for the transport behavior in the open channel for intermediate and high frequencies. For low frequencies temporal variations in the mean particle number have to be taken into account in the open channel, which cannot be captured in the more simple ring model.

  11. Rf System Requirements for JLab’s MEIC Collider Ring

    SciTech Connect

    Wang, Shaoheng; Li, Rui; Rimmer, Robert A.; Wang, Haipeng; Zhang, Yuhong

    2013-06-01

    The Medium-energy Electron Ion Collider (MEIC), proposed by Jefferson Lab, consists of a series of accelerators. At the top energy are the electron and ion collider rings. For the ion ring, it accelerates five long ion bunches to colliding energy and rebunches ions into a train of very short bunches before colliding. A set of low frequency RF system is needed for the long ion bunch energy ramping. Another set of high frequency RF cavities is needed to rebunch ions. For the electron ring, superconducting RF (SRF) cavities are needed to compensate the synchrotron radiation energy loss. The impedance of the SRF cavities must be low enough to keep the high current electron beam stable. The preliminary design requirements of these RF cavities are presented.

  12. Position Ring System using Anger Type Detectors

    SciTech Connect

    Joel S. Karp, principal investigator

    2004-12-14

    The overall objective of our project was to develop PET scanners and imaging techniques that achieve high performance and excellent image quality. Our approach was based upon 3-D imaging (no septa) with position-sensitive Anger-logic detectors, whereby the encoding ratio of resolution elements to number of photo-multiplier tube channels is very high. This design led to a series of PET systems that emphasized cost-effectiveness and practicality in a clinical environment.

  13. Documentation for the token ring network simulation system

    NASA Technical Reports Server (NTRS)

    Peden, Jeffery H.; Weaver, Alfred C.

    1990-01-01

    A manual is presented which describes the language features of the Token Ring Network Simulation System. The simulation system is a powerful simulation tool for token ring networks which allows the specification of various Medium Access Control (MAC) layer protocols as well as the specification of various features of upper layer ISO protocols. In addition to these features, it also allows the user to specify message and station classes virtually to any degree of detail desired. The choice of a language instead of an interactive system to specify network parameters was dictated by both flexibility and time considerations. The language was developed specifically for the simulation system, and is very simple. It is also user friendly in that language elements which do not apply to the case at hand are ignored rather than treated as errors.

  14. Slip-ring-based multi-transducer photoacoustic tomography system.

    PubMed

    Deng, Zijian; Li, Wenzhao; Li, Changhui

    2016-06-15

    Although the transducer array-based photoacoustic tomography (PAT) system provides fast imaging speed, its high cost and system complexity hinder its implementations. In this Letter, for the first time, to the best of our knowledge, the electrical slip ring was used to develop a PAT system that compromises the cost and the imaging speed. This system enables using multiple transducers to image the target simultaneously and continuously. In addition, it is versatile to use different transducers. The performance of this PAT system has been demonstrated by both phantom and in vivo animal experiments.

  15. A conceptual Saturn ring observer mission using standard radioisotope power systems

    NASA Technical Reports Server (NTRS)

    Abelson, Robert D.; Spilker, Thomas R.

    2006-01-01

    Saturn remains of the most fascinating planets within the solar system. To better understand the complex ring structure of this planet, a conceptual Saturn Ring Observer (SRO) mission is presented that would spend one year in close proximity to Saturn's A and B rings, and perform detailed observations and measurements of the ring particles and electric and magnetic fields.

  16. Dust in the Jovian System: Streams, Clouds and Rings

    NASA Astrophysics Data System (ADS)

    Krueger, H.; Gruen, E.

    2003-04-01

    Spacecraft investigations during the last ten years have vastly improved our knowledge about dust in the Jovian system. All Galilean satellites, and probably all smaller satellites as well, are sources of dust in the Jovian system. In-situ measurements with the dust detectors on board the Ulysses and Galileo spacecraft have for the first time demonstrated the electromagnetic interaction of charged dust grains with the interplanetary magnetic field and with a planetary magnetosphere. Jupiter's magnetosphere acts as a giant mass-velocity spectrometer for charged 10-nanometer dust grains. These grains are released from Jupiter's moon Io with a typical rate of ˜ 1 kg s-1. The seven-year long record of Galileo in-situ dust measurements revealed significant variations of the fluxes of the dust stream particles with Jovian local time which are caused by the dawn-dusk asymmetry of the Io plasma torus. The streams probe the plasma conditions in the torus, and they can be used as a potential monitor of Io's volcanic plume activity. The joint Galileo-Cassini dust measurements at Jupiter imply stream particle speeds up to 400 km s-1. All Galilean satellites are surrounded by tenuous impact-generated clouds of mostly sub-micrometer ejecta grains. Jovian rings not only exist in the well-known region of the main and gossamer rings but also much farther out. Very tenuous rings composed of mostly micron-sized grains have been detected in-situ in the region between the Galilean moons and further beyond out to ˜ 250 R_J from the planet. The dust densities there are much too low to allow detection with imaging techniques. The measurements have demonstrated that impact-ejecta derived from hypervelocity impacts onto satellites are the major constituent of dusty planetary rings. On 5 November 2002 Galileo traversed Jupiter's gossamer rings for the first time and had a close flyby at Amalthea. Several hundred dust impacts have been detected during this passage with the dust detector on

  17. READOUT SYSTEM FOR ARRAYS OF FRISCH-RING CDZNTE DETECTORS.

    SciTech Connect

    CUI, Y.; BOLOTNIKOV, A.E.; CAMARDA, G.S.; DE GERONIMO, G.; O'CONNOR, P.; JAMES, R.B.; KARGAR, A.; HARRISON, M.J.; MCGREGOR, D.S.

    2006-10-29

    Frisch-ring CdZnTe detectors have demonstrated good energy resolution for identifying isotopes, <1% FWHM at 662 keV, and good efficiency for detecting gamma rays. We will fabricate and test at Brookhaven National Laboratory an integrated module of a 64-element array of 6 x 6 x 12 mm{sup 3} Frisch-ring detectors, coupled with a readout electronics system. It supports 64 readout channels, and includes front-end electronics, signal processing circuit, USB interface and high-voltage power supply. The data-acquisition software is used to process the data stream, which includes amplitude and timing information for each detected event. This paper describes the design and assembly of the detector modules, readout electronics, and a conceptual prototype system. Some test results are also reported.

  18. Status of the SLC damping ring kicker systems

    SciTech Connect

    Mattison, T.; Cassel, R.; Donaldson, A.; Gough, D.; Gross, G.; Harvey, A.; Hutchinson, D.; Nguyen, M.

    1991-05-01

    The damping ring kickers for the SLAC Linear Collider must meet extreme requirements on rise and fall time, flatness, time and amplitude jitter and drift, voltage, repetition rate, and reliability. After several generations of improvements to the pulsers, magnets, and controls, and evolution in the understanding of the requirements, the kicker systems are no longer a serious constraint on SLC performance. Implications for future linear colliders are discussed. 14 refs.

  19. Uranus. [Scientific study of planetary structure, ring systems, and magnetosphere

    SciTech Connect

    Bergstralh, J.T.

    1987-03-01

    Observations and theoretical investigations of the Uranus (U) system from the period 1983-1986 are reviewed, with an emphasis on the Voyager 2 encounter with U on January 26, 1986. Topics addressed include the bulk U composition, structure, and heat flux; the U atmospheric composition, structure, and circulation; the U rings; the major and minor U satellites; the U magnetosphere; and the Lyman-alpha 'electroglow' observed on the sunlit hemisphere of U. 191 references.

  20. Quantum interference in an electron-hole graphene ring system

    SciTech Connect

    Smirnov, D.; Schmidt, H.; Haug, R. J.

    2013-12-04

    Quantum interference is observed in a graphene ring system via the Aharonov Bohm effect. As graphene is a gapless semiconductor, this geometry allows to study the unique situation of quantum interference between electrons and holes in addition to the unipolar quantum interference. The period and amplitude of the observed Aharonov-Bohm oscillations are independent of the sign of the applied gate voltage showing the equivalence between unipolar and dipolar interference.

  1. The fluid systems for the SLD Cherenkov ring imaging detector

    SciTech Connect

    Abe, K.; Hasegawa, K.; Hasegawa, Y.; Iwasaki, Y.; Suekane, F.; Yuta, H.; Antilogus, P.; Aston, D.; Bienz, T.; Bird, F.; Dasu, S.; Dolinsky, S.; Dunwoodie, W.; Hallewell, G.; Kawahara, H.; Kwon, Y.; Leith, D.W.G.S.; McCulloch, M.; McShurley, D.; Mueller, G.; Muller, D.; Nagamine, T.; Pavel, T.J.; Peterson, H.; Ratcliff, B.; Reif, R.; Rensing, P.; Schultz, D.; Shapiro, S.; Shaw, H.; Simopoulos, C.; Solodov, E.; Toge, N.; Vavra, J.; Watt, R.; Weber, T.; Williams, S.H.; Baird, K.; Jacques, P.; Kalelkar, M.; Plano, R.; Stamer, P.; Word, G.; Bean, A.; Caldwell, D.O.; Duboscq, J.; Huber, J.; Lu, A.; Mathys, L.; McHugh, S.; Yellin, S.; Ben-David, R.; Manly, S.; Snyder, J.; Turk, J.; Cavalli-Sforza, M.; Coyle, P.; Coyne, D.; Gagnon, P.; Liu, X.; Schneider, M.; Williams, D.A.; Coller, J.; Shank, J.T.; Whitaker, J.S.; d`Oliveira, A.; Johnson, R.A.; Martinez, J.; Nussbaum, M.; Santha, A.K.S.; Sokoloff, M.D.; Stockdale, I.; Wilson, R.J.

    1992-10-01

    We describe the design and operation of the fluid delivery, monitor and control systems for the SLD barrel Cherenkov Ring Imaging Detector (CRID). The systems deliver drift gas (C{sub 2}H{sub 6} + TMAE), radiator gas (C{sub 5}F{sub 12} + N{sub 2}) and radiator liquid (C{sub 6}F{sub 14}). Measured critical quantities such as electron lifetime in the drift gas and ultra-violet (UV) transparencies of the radiator fluids, together with the operational experience, are also reported.

  2. Reliability analysis for LEB ring magnet power system in SSC

    SciTech Connect

    Smedley, K.

    1991-11-01

    The LEB ring magnet power system contains six subsystems, supervisory control, power supplies, regulation, DC bus, resonant cells, and fault sensing network. The system availability of the total LEB RMPS is required to be 0.999. The work in this paper is to allocate the overall LEB RMPS reliability requirement into reliability requirements for each of the subsystems and lower-tier items. The Feasibility-of-Objective technique combining with engineering experience is the key for the allocation. MIL-HDBK-217F is used to derate SCR components. 7 refs., 5 figs.

  3. High resolution upgrade of the ATF damping ring BPM system

    SciTech Connect

    Terunuma, N.; Urakawa, J.; Frisch, J.; May, J.; McCormick, D.; Nelson, J.; Seryi, A.; Smith, T.; Woodley, M.; Briegel, C.; Dysert, R.; /Fermilab

    2008-05-01

    A beam position monitor (BPM) upgrade at the KEK Accelerator Test Facility (ATF) damping ring has been accomplished in its first stage, carried out by a KEK/FNAL/SLAC collaboration under the umbrella of the global ILC R&D effort. The upgrade consists of a high resolution, high reproducibility read-out system, based on analog and digital downconversion techniques, digital signal processing, and also tests a new automatic gain error correction schema. The technical concept and realization, as well as preliminary results of beam studies are presented.

  4. O-Ring sealing arrangements for ultra-high vacuum systems

    DOEpatents

    Kim, Chang-Kyo; Flaherty, Robert

    1981-01-01

    An all metal reusable O-ring sealing arrangement for sealing two concentric tubes in an ultra-high vacuum system. An O-ring of a heat recoverable alloy such as Nitinol is concentrically positioned between protruding sealing rings of the concentric tubes. The O-ring is installed between the tubes while in a stressed martensitic state and is made to undergo a thermally induced transformation to an austenitic state. During the transformation the O-ring expands outwardly and contracts inwardly toward a previously sized austenitic configuration, thereby sealing against the protruding sealing rings of the concentric tubes.

  5. TRANSIT MODEL OF PLANETS WITH MOON AND RING SYSTEMS

    SciTech Connect

    Tusnski, Luis Ricardo M.; Valio, Adriana E-mail: avalio@craam.mackenzie.br

    2011-12-10

    Since the discovery of the first exoplanets, those most adequate for life to begin and evolve have been sought. Due to observational bias, however, most of the discovered planets so far are gas giants, precluding their habitability. However, if these hot Jupiters are located in the habitable zones of their host stars, and if rocky moons orbit them, then these moons may be habitable. In this work, we present a model for planetary transit simulation considering the presence of moons and planetary rings around a planet. The moon's orbit is considered to be circular and coplanar with the planetary orbit. The other physical and orbital parameters of the star, planet, moon, and rings can be adjusted in each simulation. It is possible to simulate as many successive transits as desired. Since the presence of spots on the surface of the star may produce a signal similar to that of the presence of a moon, our model also allows for the inclusion of starspots. The result of the simulation is a light curve with a planetary transit. White noise may also be added to the light curves to produce curves similar to those obtained by the CoRoT and Kepler space telescopes. The goal is to determine the criteria for detectability of moons and/or ring systems using photometry. The results show that it is possible to detect moons with radii as little as 1.3 R{sub Circled-Plus} with CoRoT and 0.3 R{sub Circled-Plus} with Kepler.

  6. Androgynous, Reconfigurable Closed Loop Feedback Controlled Low Impact Docking System With Load Sensing Electromagnetic Capture Ring

    NASA Technical Reports Server (NTRS)

    Lewis, James L. (Inventor); Carroll, Monty B. (Inventor); Morales, Ray H. (Inventor); Le, Thang D. (Inventor)

    2002-01-01

    The present invention relates to a fully androgynous, reconfigurable closed loop feedback controlled low impact docking system with load sensing electromagnetic capture ring. The docking system of the present invention preferably comprises two Docking- assemblies, each docking assembly comprising a load sensing ring having an outer face, one of more electromagnets, one or more load cells coupled to said load sensing ring. The docking assembly further comprises a plurality of actuator arms coupled to said load sensing ring and capable of dynamically adjusting the orientation of said load sensing ring and a reconfigurable closed loop control system capable of analyzing signals originating from said plurality of load cells and of outputting real time control for each of the actuators. The docking assembly of the present invention incorporates an active load sensing system to automatically dynamically adjust the load sensing ring during capture instead of requiring significant force to push and realign the ring.

  7. The Second Ring-Moon System of Uranus: Discovery and Dynamics

    NASA Technical Reports Server (NTRS)

    Showalter, M. R.; Lissauer, J. J.

    2005-01-01

    Deep exposures of Uranus taken with the Hubble Space Telescope reveal two small moons and two faint rings. All orbit outside of Uranus's previously known (main) ring system, but interior to the large, classical moons. The outer new moon, U XXVI Mab, orbits at roughly twice the radius of the main rings and shares its orbit with a dust ring. The second moon, U XXVII Cupid, orbits just interior to the satellite Belinda. A second ring falls between the orbits of Portia and Rosalind, in a region with no known source bodies. Collectively, these constitute a densely-packed, rapidly varying and possibly unstable dynamica1 system.

  8. The second ring-moon system of Uranus: discovery and dynamics.

    PubMed

    Showalter, Mark R; Lissauer, Jack J

    2006-02-17

    Deep exposures of Uranus taken with the Hubble Space Telescope reveal two small moons and two faint rings. All of them orbit outside of Uranus's previously known (main) ring system but are interior to the large, classical moons. The outer new moon, U XXVI Mab, orbits at roughly twice the radius of the main rings and shares its orbit with a dust ring. The second moon, U XXVII Cupid, orbits just interior to the satellite Belinda. A second ring falls between the orbits of Portia and Rosalind, in a region with no known source bodies. Collectively, these constitute a densely packed, rapidly varying, and possibly unstable dynamical system.

  9. Saturn's F ring and shepherd satellites a natural outcome of satellite system formation

    NASA Astrophysics Data System (ADS)

    Hyodo, Ryuki; Ohtsuki, Keiji

    2015-09-01

    Saturn's F ring is a narrow ring of icy particles, located 3,400 km beyond the outer edge of the main ring system. Enigmatically, the F ring is accompanied on either side by two small satellites, Prometheus and Pandora, which are called shepherd satellites. The inner regular satellites of giant planets are thought to form by the accretion of particles from an ancient massive ring and subsequent outward migration. However, the origin of a system consisting of a narrow ring and shepherd satellites remains poorly understood. Here we present N-body numerical simulations to show that a collision of two of the small satellites that are thought to accumulate near the main ring's outer edge can produce a system similar to the F ring and its shepherd satellites. We find that if the two rubble-pile satellites have denser cores, such an impact results in only partial disruption of the satellites and the formation of a narrow ring of particles between two remnant satellites. Our simulations suggest that the seemingly unusual F ring system is a natural outcome at the final stage of the formation process of the ring-satellite system of giant planets.

  10. Photometric Analysis of the Jovian Ring System and Modeling of Ring Origin and Evolution

    NASA Technical Reports Server (NTRS)

    Esposito, L. W.

    2003-01-01

    We have successfully completed the work described in our proposal. The work supported by this grant resulted in the publication of the following paper: Brooks, S. M., L. W. Esposito, M. R. Showalter, and H. B. Throop. 2002. The size distribution of Jupiter's main ring from Galileo imaging and spectroscopy. Icarus, in press. This was also the major part of Dr. Shawn Brooks PhD dissertation. Dr. Brooks gave oral presentations on this work at the Lunar and Planetary Conference, the annual meetings of the Division for Planetary Sciences of the American Astronomical Society, the annual meetings of the European Geophysical Society, the international Jupiter Conference in Boulder, the Jupiter after Galileo and Cassini Conference in Lisbon and to the Working Group in Non-Linear Dynamics in Potsdam, Germany. This work was reviewed in: Esposito, L. W. 2002. Planetary rings. Rep. hog. Phys. 65, 1741-1783. Planetary rings. LASP reprint 874. Online at http://stacks.iop.org/RoPP/65/1741. Dr. Esposito gave presentations at schools and over the internet on the results of this work. Dr. Brooks lectured in undergraduate and graduate classes on Jupiter's rings, and on the meaning of his research. In August 2003, Dr. Shawn Brooks received the Phd degree from the University of Colorado in Astrophysical and Planetary Sciences.

  11. Arrayed Micro-Ring Spectrometer System and Method of Use

    NASA Technical Reports Server (NTRS)

    Choi, Sang H. (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

    2012-01-01

    A spectrometer system includes an array of micro-zone plates (MZP) each having coaxially-aligned ring gratings, a sample plate for supporting and illuminating a sample, and an array of photon detectors for measuring a spectral characteristic of the predetermined wavelength. The sample plate emits an evanescent wave in response to incident light, which excites molecules of the sample to thereby cause an emission of secondary photons. A method of detecting the intensity of a selected wavelength of incident light includes directing the incident light onto an array of MZP, diffracting a selected wavelength of the incident light onto a target focal point using the array of MZP, and detecting the intensity of the selected portion using an array of photon detectors. An electro-optic layer positioned adjacent to the array of MZP may be excited via an applied voltage to select the wavelength of the incident light.

  12. Results from a survey of the dynamics shaping Uranus' Mab/μ-ring system

    NASA Astrophysics Data System (ADS)

    Kumar, Kartik; de Pater, Imke; Showalter, Mark R.

    2014-11-01

    Based on Hubble Space Telescope (HST) data, Showalter and Lissauer (2006) reported the discovery of two faint rings beyond Uranus’ main rings: the ν- and μ- rings. They constitute Uranus' outer ring system and are located beyond the ɛ-ring but interior to the large classical moons. After co-adding a series of HST images, Showalter and Lissauer (2006) obtained radial profiles for both new rings. They discovered that the peak radial intensity of the μ-ring aligns closely with the orbit of Mab. Along with numerous other observations, this points to the fact that the Mab/μ-ring system is highly coupled.The discovery of the μ-ring has led to open questions about dust dynamics beyond Uranus' main rings. Like Saturn's E-ring, observations reveal that the μ-ring is blue, indicative of a pre-dominance of sub-micron-sized particles (de Pater et al., 2006). The E-ring results from plumes on Enceladus' south pole, however the origin of the μ-ring remains a mystery. The latter is likely fed by ejecta from micro-meteorite impacts with Mab, much like Jupiter's faint rings are regenerated by companion (small) moons (Burns et al., 1999). The μ-ring's steep size-distribution suggests that there is an unknown mechanism at play that hides or removes large dust particles. We present results from an investigation into the forces shaping the μ-ring. To simulate the motion of dust in the Mab/μ-ring system, we developed a numerical toolbox (Dustsim; Kumar et al., 2015) that uses Tudat (Kumar et al., 2012). We performed integrations using Dustsim that included the effects of Uranus' gravity field, titled magnetic moment, solar radiation pressure, and collisions with a putative suite of large μ-ring bodies, hypothesized as the cause of Mab's anomalous orbital motion (Kumar et al., 2014). Following on from previous studies (e.g., Sfair and Giuliatti Winter, 2009; Sfair and Giuliatti Winter, 2012), we present a survey of the expected lifetime of μ-ring dust, as a function of

  13. The Secular Evolution of a Close Ring-Satellite System

    NASA Astrophysics Data System (ADS)

    Hahn, Joseph M.

    2006-06-01

    We use the rings model of Hahn (2003) to examine the secular evolution of a small satellite orbiting in a narrow gap in a dense planetary ring. The model shows that if the satellite has a small eccentricity, then its secular perturbations excites the eccentricities of the nearest ring particles orbiting at the gap edge. The ring's self-gravity then allows that disturbance to propagate outwards and across the ring in the form of a spiral density wave. Similarly, an inclined satellite also launches a spiral bending wave that propagates radially outwards from the gap's outer edge. When we use the rings model to consider Pan, which inhabits the Encke gap in Saturn's main A ring, we find that the satellite excites low amplitude spiral waves having very long wavelengths that are hundreds of km. Whether these low-amplitude waves might be observed by the Cassini spacecraft is also under investigation. The excitation of these waves transmits angular momentum from the satellite to the ring, so this form of wave-action tends to damp the satellite's eccentricity and inclination. Note that the fates of a satellite's eccentricity and inclination are uncertain when it orbits in a gap. This is due to the competition between the satellite's many Lindblad resonances in the ring, which excites the satellite's eccentricity, and and its corotation resonances, which might or might not damp its eccentricity (Goldreich and Tremaine 1980, Goldreich and Sari 2003). The satellite's inclination is also precarious, since its many vertical resonances in the ring tends to pump up the satellite's inclination (Borderies et al 1984). However, the rings model shows that the satellite's secular perturbation of the ring tends to damp its eccentricity and inclination at rates that dwarf the excitation mechanisms. The stability of the satellite's eccentricity and inclination thus seems assured.

  14. Development of an Acoustic Levitation Linear Transportation System Based on a Ring-type Structure.

    PubMed

    Thomas, Gilles; Andrade, Marco Aurelio; Adamowski, Julio; Silva, Emilio

    2017-02-23

    A linear acoustic levitation transportation system based on a ring-type vibrator is presented. The system is composed by two 21 kHz Langevin transducers connected to a ring-shaped structure formed by two semicircular sections and two flat plates. In this system, a flexural standing wave is generated along the ring structure, producing an acoustic standing wave between the vibrating ring and a plane reflector located at a distance of approximately a half wavelength from the ring. The acoustic standing wave in air has a series of pressure nodes, where small particles can be levitated and transported. The ring-type transportation system was designed and analyzed by using the Finite Element Method (FEM). Additionally, a prototype was built and the acoustic levitation and transport of a small polystyrene particle was demonstrated.

  15. Chariklo's ring system 3. Exploration of possible Chariklo spin/ring orbit resonances

    NASA Astrophysics Data System (ADS)

    Sicardy, Bruno; El Moutamid, Maryame; Leiva, Rodrigo; Berard, Diane; Renner, Stéfan

    2016-10-01

    Two dense and narrow rings orbit the Centaur object Chariklo at respective radii of 391±3 and 405±3 km (Braga-Ribas et al., Nature 508, 72, 2014).With a rotation period of PC = 7.004 ± 0.036 h (Fornasier et al. A.&A. 568, L11, 2014), Chariklo may adopt either a MacLaurin spheroid or a Jacobi ellipsoid shape, depending on density (and assuming hydrostatic equilibrium). Moreover, being a small icy body, Chariklo is prone to topographic features at several-kilometer scales.Meanwhile, scarce information on Chariklo's size and shape is presently available from occultation works, as only five chords have been obtained during three occultations that have been observed in 2013 and 2014. Those data are consistent with a MacLaurin shape with axes a, b, c ~ 133x133x110 km and mass MC ~ (1-2)x1019 kg, or with a Jacobi shape with a, b, c ~ 167x133x124 km and MC ~ 0.6-0.7x1019 kg, see the companion paper by Leiva et al.Those values imply a corotation radius between 190 and 280 km, depending on the adopted value of MC. This is well inside the ring radii, ruling out the corotation resonance as the main driver for the ring orbital dynamics.The ring orbital period could lie between Pr ~12 and 22 h, depending on MC, thus allowing possible resonances with Chariklo's spin rate ΩC. Two models will be explored. One model assumes a MacLaurin shape with a topographic feature of mass m that acts as perturbing satellites with orbital radius and period a and PC, respectively. This creates 1st order Linblad-type resonances of the kind Pr/PC = m+1/m (m integer) whose possible effects on the ring structure will be evaluated.The other model assumes a Jacobi shape that creates a perturbing potential GMc/r3 [(A+B-2C)2 + (3/2)(A-B).cos(2θ)] with θ= λ-ΩC.t in Chariklo's equatorial plane, where A, B, C are the moments of inertia around a, b, c, respectively, and λ is the mean longitude. This creates qth order Linblad-type resonances of the kind Pr/PC = q+2/q (q integer) that will also be

  16. Near-infrared spectra of the uranian ring system

    NASA Astrophysics Data System (ADS)

    de Kleer, Katherine; de Pater, Imke; Ádámkovics, Máté; Hammel, Heidi

    2013-09-01

    We present the first high-resolution near-infrared (1.18-2.38 μm) spectrum of the rings of Uranus, as observed with adaptive optics on the W.M. Keck II telescope in August 2010. We derive ring equivalent widths, as well as ring and particle reflectivities for the ɛ ring and ringlet groups based on H- and K-band data. We find the rings to be gray, indicating that they are dominated by large particles rather than dust, and we find no evidence for water ice. We present a reflectivity spectrum for the ɛ ring alone, which we also find to be consistent with a flat spectrum. We derive H-band ring particle reflectivities of 0.022 ± 0.010, 0.051 ± 0.009 0.042 ± 0.012, and 0.043 ± 0.001 and K-band ring particle reflectivities of 0.016 ± 0.010, 0.034 ± 0.012, 0.047 ± 0.008 and 0.041 ± 0.002 for the 456, αβ, ηγδ, and ɛ ring groups. Previous observations have found ring particle reflectivities in the 0.033-0.044 range (de Pater, I., Gibbard, S., Macintosh, B.A., Roe, H.G. [2002]. Icarus 160, 359-374; Gibbard, S.G., de Pater, I., Hammel, H.B. [2005]. Icarus 174, 253-262), and are generally consistent with our results.

  17. An objective reference system for studying rings in the ocean

    NASA Astrophysics Data System (ADS)

    Castelão, Guilherme P.; Irber, Luiz C.; Villas Boas, Ana B. M.

    2013-12-01

    Rings are marine vortices with a scale of hundreds of kilometers that can last for months, whose associated transport and mixing play an important role in the ocean dynamics. Such features are traditionally treated as a geostrophic flow, but since the centrifugal acceleration is not negligible in the inner core, the cyclo-geostrophic balance is a better approximation for the rings. In the present work, we describe a novel objective technique to identify the ring center, which is used as the origin of a convenient framework to handle rings under the cyclo-geostrophic balance. Furthermore, we correct the velocity field by the translation to isolate the swirl movement, a procedure ignored by other methodologies. We show that the lack of such correction would lead to an error of 30 km on the center definition of a ship surveyed North Brazil Current Ring with 160 km of radius. Another distinct characteristic of our approach is the flexibility in the spatio-temporal structure of the data, because it allows for ungridded data, an important ability for in situ observations. That also enables the use of a hybrid dataset composed from different instruments. The error on the Monte Carlo experiments to identify the center of the propagating ring is less than 10 km, and depends on the level of noise, sampling strategy, and strength of the ring, among other factors. This technique was fully implemented in PyRings, an open Python library with a collection of procedures to handle oceanic rings and mesoscale eddies in general.

  18. Stereocontrolled Additions to a Rigid Bicyclo [3.3.0] Octane Ring System

    DTIC Science & Technology

    2008-05-05

    reagent added to the competing electrophilic carbonyl of the lactone group on the opposite ring with subsequent ring opening upon acidic work-up...carbon and a stereocenter. In actuality, the cuprate reagent added to the competing electrophilic carbonyl of the lactone group on the opposite ring...According to this accepted mechanism, the number four carbon of a conjugated system serves as the electrophilic center to be attacked by a

  19. Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Cuzzi, J. N.

    2014-12-01

    The rings are changing before our eyes; structure varies on all timescales and unexpected things have been discovered. Many questions have been answered, but some answers remain elusive (see Cuzzi et al 2010 for a review). Here we highlight the major ring science progress over the mission to date, and describe new observations planned for Cassini's final three years. Ring Composition and particle sizes: The rings are nearly all water ice with no other ices - so why are they reddish? The C Ring and Cassini Division are "dirtier" than the more massive B and A Rings, as shown by near-IR and, recently, microwave observations. Particle sizes, from stellar and radio occultations, vary from place to place. Ring structure, micro and macro: numerous spiral density waves and ubiquitous "self-gravity wakes" reveal processes which fostered planet formation in the solar system and elsewhere. However, big puzzles remain regarding the main ring divisions, the C Ring plateau structures, and the B Ring irregular structure. Moonlets, inside and out, seen and unseen: Two gaps contain sizeable moonlets, but more gaps seem to contain none; even smaller embedded "propeller" objects wander, systematically or randomly, through the A ring. Rubble pile ringmoons just outside the rings may escaped from the rings, and the recently discovered "Peggy" may be trying this as we watch. Impact bombardment of the rings: Comet fragments set the rings to rippling on century-timescales, and boulders crash through hourly; meanwhile, the constant hail of infalling Kuiper belt material has a lower mass flux than previously thought. Origin and Age of the Rings: The ring mass and bombardment play key roles. The ring mass is well known everywhere but in the B Ring (where most of it is). New models suggest how tidal breakup of evolving moons may have formed massive ancient rings, of which the current ring is just a shadow. During its last three years, the Cassini tour profile will allow entirely new

  20. Multiple internal seal ring micro-electro-mechanical system vacuum packaging method

    NASA Technical Reports Server (NTRS)

    Hayworth, Ken J. (Inventor); Yee, Karl Y. (Inventor); Shcheglov, Kirill V. (Inventor); Bae, Youngsam (Inventor); Wiberg, Dean V. (Inventor); Challoner, A. Dorian (Inventor); Peay, Chris S. (Inventor)

    2008-01-01

    A Multiple Internal Seal Ring (MISR) Micro-Electro-Mechanical System (MEMS) vacuum packaging method that hermetically seals MEMS devices using MISR. The method bonds a capping plate having metal seal rings to a base plate having metal seal rings by wafer bonding the capping plate wafer to the base plate wafer. Bulk electrodes may be used to provide conductive paths between the seal rings on the base plate and the capping plate. All seals are made using only metal-to-metal seal rings deposited on the polished surfaces of the base plate and capping plate wafers. However, multiple electrical feed-through metal traces are provided by fabricating via holes through the capping plate for electrical connection from the outside of the package through the via-holes to the inside of the package. Each metal seal ring serves the dual purposes of hermetic sealing and providing the electrical feed-through metal trace.

  1. Ring lens focusing and push-pull tracking scheme for optical disk systems

    NASA Technical Reports Server (NTRS)

    Gerber, R.; Zambuto, J.; Erwin, J. K.; Mansuripur, M.

    1993-01-01

    An experimental comparison of the ring lens and the astigmatic techniques of generating focus-error-signal (FES) in optical disk systems reveals that the ring lens generates a FES over two times steeper than that produced by the astigmat. Partly due to this large slope and, in part, because of its diffraction-limited behavior, the ring lens scheme exhibits superior performance characteristics. In particular the undesirable signal known as 'feedthrough' (induced on the FES by track-crossings during the seek operation) is lower by a factor of six compared to that observed with the astigmatic method. The ring lens is easy to align and has reasonable tolerance for positioning errors.

  2. The Ring System of Uranus: Flat as a Pancake, Sprinkled with Dust

    SciTech Connect

    de Pater, I; Gibbard, S G; Hammel, H B

    2005-02-02

    We present a high quality image of the uranian ring system, obtained in July 2004 at 2.2 {micro}m with the adaptive optics camera NIRC2 on the Keck II telescope. Using these data, we report the first ground-based image of the ring 1986U2R, seen only once before by the Voyager spacecraft. We show that this ring extends inward to {approx} 7000 km above the Uranus cloud deck. Its VIF (total vertically integrated I/F) is {approx} 100 m. We further detected narrow sheets of dust in between the {delta} and {epsilon} rings, and in between rings 4 and {alpha}, with a VIF of 14 and 20 m, respectively. Surprisingly, we find that the particles in Uranus' 9 main rings are distributed within a mono-layer, rather than the usually adopted poly-layer model. We come to this conclusion via a comparison of the VIF as derived from our 2003 data at a ring opening angle B {approx} 18{sup o} (from Gibbard et al. 2004) with those derived in this paper at B {approx} 11{sup o}. We show that the VIF increases approximately as 1/sinB at the ring ansae, but is independent of sinB in front of the disk. This combination of factors can only be explained if the particles in Uranus' rings are distributed in a mono-layer, a configuration which makes the uranian system unique amongst the giant planets.

  3. Note: O-ring stack system for electron gun alignment

    SciTech Connect

    Park, In-Yong; Cho, Boklae; Han, Cheolsu; Shin, Seungmin; Lee, Dongjun; Ahn, Sang Jung

    2015-01-15

    We present a reliable method for aligning an electron gun which consists of an electron source and lenses by controlling a stack of rubber O-rings in a vacuum condition. The beam direction angle is precisely tilted along two axes by adjusting the height difference of a stack of O-rings. In addition, the source position is shifted in each of three orthogonal directions. We show that the tilting angle and linear shift along the x and y axes as obtained from ten stacked O-rings are ±2.55° and ±2 mm, respectively. This study can easily be adapted to charged particle gun alignment and adjustments of the flange position in a vacuum, ensuring that its results can be useful with regard to electrical insulation between flanges with slight modifications.

  4. Note: O-ring stack system for electron gun alignment

    NASA Astrophysics Data System (ADS)

    Park, In-Yong; Cho, Boklae; Han, Cheolsu; Shin, Seungmin; Lee, Dongjun; Ahn, Sang Jung

    2015-01-01

    We present a reliable method for aligning an electron gun which consists of an electron source and lenses by controlling a stack of rubber O-rings in a vacuum condition. The beam direction angle is precisely tilted along two axes by adjusting the height difference of a stack of O-rings. In addition, the source position is shifted in each of three orthogonal directions. We show that the tilting angle and linear shift along the x and y axes as obtained from ten stacked O-rings are ±2.55° and ±2 mm, respectively. This study can easily be adapted to charged particle gun alignment and adjustments of the flange position in a vacuum, ensuring that its results can be useful with regard to electrical insulation between flanges with slight modifications.

  5. Voyager Saturnian ring measurements and the early history of the solar system

    NASA Technical Reports Server (NTRS)

    Alfven, H.; Axnaes, I.; Brenning, N.; Lindquist, P. A.

    1985-01-01

    The mass distribution in the Saturnian ring system is investigated and compared with predictions from plasma cosmogony. According to this theory, the matter in the rings was once a magnetized plasma, in which gravitation is balanced by the centrifugal and electromagnetic forces. As the plasma is neutralized, the electromagnetic forces disappear and the matter falls in to 2/3 of the original saturnocentric distance. This causes the cosmogonic shadow effect, demonstrated for the large scale structure of the Saturnian ring system. It is shown that many structures of the present ring system can be understood as shadows and antishadows of cosmogonic origin. These appear in the form of double rings centered around a position a factor 0.64 (slightly 2/3) closer to Saturn than the causing feature. Voyager data agree with an accuracy 1%.

  6. Gaseous toroid around Saturn. [Saturnian ring system for atomic hydrogen trapping in Titan atmospheric model

    NASA Technical Reports Server (NTRS)

    Mcdonough, T. R.

    1974-01-01

    The trapping of Titan's escaping atmosphere in the Saturnian system by a toroidal ring is discussed. The radius of the toroid is comparable to Titan's orbit, or about ten times larger than the visible rings. Theoretical atmospheric models are formulated that consider Saturn's gravitational attraction and magnetospheric properties in forming this toroid and in protecting toroid particles from direct ionization by solar wind particles.

  7. Palladium-catalyzed arylation of 2H-chromene: a new entry to pyrano[2,3-c]carbazoles.

    PubMed

    Ranjith Reddy, K; Siva Reddy, A; Dhaked, Devendra K; Rasheed, S K; Pathania, Anup Singh; Shankar, Ravi; Malik, Fayaz; Das, Parthasarathi

    2015-09-21

    Pyrano[2,3-c]carbazoles which are biologically valuable and synthetically challenging frameworks are synthesized in high yields over five steps from commercially available resorcinol. Palladium-catalyzed arylation remains a key step in this novel strategy. The versatility of this protocol has been demonstrated by the synthesis of naturally occurring alkaloid clauraila C and 7-methoxyglycomaurin. The anti-proliferative activity of these designed compounds (5a, 5f, and 5l) has been evaluated in a cancer cell line (MOLT-4). The molecular docking study revealed that this pyrano[2,3-c]carbazole class of molecules selectively occupies the colchicine binding site of the tubulin-polymer.

  8. Detecting ring systems around exoplanets using high resolution spectroscopy: the case of 51 Pegasi b

    NASA Astrophysics Data System (ADS)

    Santos, N. C.; Martins, J. H. C.; Boué, G.; Correia, A. C. M.; Oshagh, M.; Figueira, P.; Santerne, A.; Sousa, S. G.; Melo, C.; Montalto, M.; Boisse, I.; Ehrenreich, D.; Lovis, C.; Pepe, F.; Udry, S.; Garcia Munoz, A.

    2015-11-01

    Aims: In this paper we explore the possibility that the recently detected reflected light signal of 51 Peg b could be caused by a ring system around the planet. Methods: We use a simple model to compare the observed signal with the expected signal from a short-period giant planet with rings. We also use simple dynamical arguments to understand the possible geometry of such a system. Results: We provide evidence that, to a good approximation, the observations are compatible with the signal expected from a ringed planet, assuming that the rings are non-coplanar with the orbital plane. However, based on dynamical arguments, we also show that this configuration is unlikely. In the case of coplanar rings we then demonstrate that the incident flux on the ring surface is about 2% the value received by the planet, a value that renders the ring explanation unlikely. Conclusions: The results suggest that the signal observed cannot in principle be explained by a planet+ring system. We discuss, however, the possibility of using reflected light spectra to detect and characterize the presence of rings around short-period planets. Finally, we show that ring systems could have already been detected by photometric transit campaigns, but their signal could have been easily misinterpreted by the expected light curve of an eclipsing binary. Based on observations collected at ESO facilities under program 091.C-0271 (with the HARPS spectrograph at the ESO 3.6-m telescope, La Silla-Paranal Observatory).Appendices are available in electronic form at http://www.aanda.org

  9. A hybrid-structure of a cavity polariton system and an optical-ring

    NASA Astrophysics Data System (ADS)

    Wang, Jian; Xie, Wei; Zhang, Long; Wang, Yinglei; Gu, Jie; Hu, Tao; Wu, Lin; Chen, Zhanghai

    2015-06-01

    We demonstrate a hybrid-structure of a ZnO polariton system and an optical-ring in this work. In this structure, we create room-temperature polariton condensate in the ZnO nanowire. The coherent light emission from the polariton condensate is coupled to the ring, and the coherence of the coupled light is examined by Young interference experiment using a photoluminescence mapping system. Finally, the efficiency of the waveguide of the coupled light in the ring has been carefully discussed.

  10. Synthesis of fused indazole ring systems and application to nigeglanine hydrobromide.

    PubMed

    Sather, Aaron C; Berryman, Orion B; Rebek, Julius

    2012-03-16

    The single-step synthesis of fused tricyclic pyridazino[1,2-a]indazolium ring systems is described. Structural details revealed by crystallography explain the unexpected reactivity. The method is applied to the gram scale synthesis of nigeglanine hydrobromide.

  11. Feasibility study of shape memory alloy ring spring systems for self-centring seismic resisting devices

    NASA Astrophysics Data System (ADS)

    Fang, Cheng; Yam, Michael C. H.; Lam, Angus C. C.; Zhang, Yanyang

    2015-07-01

    Shape memory alloys (SMAs) have recently emerged as promising material candidates for structural seismic resisting purposes. Most of the existing SMA-based strategies, however, are based on the wire or rod form of SMAs, where issues such as gripping complexity and fracture may exist. This paper presents a proof-of-concept study on an innovative type of SMA-based self-centring system, namely, a superelastic SMA ring spring system. The proposed system includes a series of inner high-strength steel (HSS) rings and outer superelastic SMA rings stacked in alternation with mating taper faces, where the resisting load is provided by the wedging action which tends to expand the outer rings and concurrently to squeeze the inner rings. The superelastic effect of the SMA offers energy dissipation and a driving force for recentring, and the frictional effect over the taper face further contributes to the overall resisting load and energy dissipation. The feasibility of the new system is carefully examined via numerical studies considering the parameters of ring thickness, taper angle, and coefficient of friction. The key hysteretic responses, including resisting load, stiffness, stress distributions, source of residual deformation, energy dissipation, and equivalent viscous damping, are discussed in detail. The behaviour of the SMA ring springs is also studied via analytical models, and the analytical predictions are found to agree well with the numerical results. Finally, two practical applications of the new system, namely self-centring HS-SMA ring spring connections, and self-centring SMA ring spring dampers, are discussed via comprehensive numerical studies.

  12. Hydrodynamic optimization of trust ring pump and lubricating oil system for large hydroelectric units thrust bearing

    NASA Astrophysics Data System (ADS)

    Lai, X.; Lu, Z.; Zhang, X.; Yang, S.

    2014-03-01

    Thrust-ring-pump is a kind of extreme-low specific speed centrifugal pump with special structure as numerous restrictions form thrust bearing and operation conditions of hydro turbine generator unit. Because the oil circulating and cooling system with thrust-ring- pump has a lot of advantages in maintenance and compactness in structure, it has widely been used in large and medium-sized hydro-generator units. Since the diameter and the speed of the thrust ring is limited by the generator set, the matching relationship between the flow passage inside the thrust ring (equivalent to impeller) and oil bath (equivalent to volute) has great influence on hydrodynamic performance of thrust-ring-pump, additionally, the head and discharge are varying with the operation conditions of hydro-generator unit and characteristic of the oil circulating and cooling system. As so far, the empirical calculation method is employed during the actual engineering design, in order to guarantee the operating performance of the oil circulating and cooling system with thrust-ring-pump at different conditions, a collaborative hydrodynamic design and optimization of both the oil circulating and cooling system and thrust-ring-pump is purposed in this paper. Firstly, the head and discharge required at different conditions are decided by 1D flow numerical simulation of the oil circulating and cooling system. Secondly, the flow passages of thrust-ring-pump are empirically designed under the restrictions of diameter and the speed of the thrust ring according to the head and discharge from the simulation. Thirdly, the flow passage geometry matching optimization between holes inside the thrust ring and oil bath is implemented by means of 3D flow simulation and performance prediction. Then, the pumps and the oil circulating and cooling system are collaborative hydrodynamic optimized with predicted head- discharge curve and the efficiency-discharge curve of thrust-ring-pump. The presented methodology has

  13. A Saturn Ring Observer Mission Using Multi-Mission Radioisotope Power Systems

    NASA Astrophysics Data System (ADS)

    Abelson, Robert D.; Spilker, Thomas R.; Shirley, James H.

    2006-01-01

    Saturn remains one of the most fascinating planets within the solar system. To better understand the complex ring structure of this planet, a conceptual Saturn Ring Observer (SRO) mission is presented that would spend one year in close proximity to Saturn's A and B rings, and perform detailed observations and measurements of the ring particles and electric and magnetic fields. The primary objective of the mission would be to understand ring dynamics, including the microphysics of individual particles and small scale (meters to a few kilometers) phenomena such as particle agglomeration behavior. This would be accomplished by multispectral imaging of the rings at multiple key locations within the A and B rings, and by ring-particle imaging at an unprecedented resolution of 0.5 cm/pixel. The SRO spacecraft would use a Venus-Earth-Earth-Jupiter Gravity Assist (VEEJGA) and be aerocaptured into Saturn orbit using an advanced aeroshell design to minimize propellant mass. Once in orbit, the SRO would stand off from the ring plane 1 to 1.4 km using chemical thrusters to provide short propulsive maneuvers four times per revolution, effectively causing the SRO vehicle to ``hop'' above the ring plane. The conceptual SRO spacecraft would be enabled by the use of a new generation of multi-mission Radioisotope Power Systems (RPSs) currently being developed by NASA and DOE. These RPSs include the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) and Stirling Radioisotope Generator (SRG). The RPSs would generate all necessary electrical power (>=330 We at beginning of life) during the 10-year cruise and 1-year science mission (~11 years total). The RPS heat would be used to maintain the vehicle's operating and survival temperatures, minimizing the need for electrical heaters. Such a mission could potentially launch in the 2015-2020 timeframe, with operations at Saturn commencing in approximately 2030.

  14. A Saturn Ring Observer Mission Using Multi-Mission Radioisotope Power Systems

    SciTech Connect

    Abelson, Robert D.; Spilker, Thomas R.; Shirley, James H.

    2006-01-20

    Saturn remains one of the most fascinating planets within the solar system. To better understand the complex ring structure of this planet, a conceptual Saturn Ring Observer (SRO) mission is presented that would spend one year in close proximity to Saturn's A and B rings, and perform detailed observations and measurements of the ring particles and electric and magnetic fields. The primary objective of the mission would be to understand ring dynamics, including the microphysics of individual particles and small scale (meters to a few kilometers) phenomena such as particle agglomeration behavior. This would be accomplished by multispectral imaging of the rings at multiple key locations within the A and B rings, and by ring-particle imaging at an unprecedented resolution of 0.5 cm/pixel. The SRO spacecraft would use a Venus-Earth-Earth-Jupiter Gravity Assist (VEEJGA) and be aerocaptured into Saturn orbit using an advanced aeroshell design to minimize propellant mass. Once in orbit, the SRO would stand off from the ring plane 1 to 1.4 km using chemical thrusters to provide short propulsive maneuvers four times per revolution, effectively causing the SRO vehicle to 'hop' above the ring plane. The conceptual SRO spacecraft would be enabled by the use of a new generation of multi-mission Radioisotope Power Systems (RPSs) currently being developed by NASA and DOE. These RPSs include the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) and Stirling Radioisotope Generator (SRG). The RPSs would generate all necessary electrical power ({>=}330 We at beginning of life) during the 10-year cruise and 1-year science mission ({approx}11 years total). The RPS heat would be used to maintain the vehicle's operating and survival temperatures, minimizing the need for electrical heaters. Such a mission could potentially launch in the 2015-2020 timeframe, with operations at Saturn commencing in approximately 2030.

  15. Submission of Earth-based ring occultation observations to the NASA planetary data system rings discipline node

    NASA Technical Reports Server (NTRS)

    French, Richard G.

    1993-01-01

    This is a technical report summarizing our progress in our program of contributing high quality Earth-based occultation observations to NASA's Planetary Data System (PDS) Rings Node. During our first year of funding, we selected five data sets for eventual inclusion in the PDS Rings Node. These were Uranus occultation observations obtained by the PI and co-workers from the IRTF of event stars U34 (26 April 1986), U1052 (5 May 1988), U65 (21 June 1990), U7872 (25 June 1991), and U7808 (28 June 1991). In our original proposal, we described four tasks: data sets to a common format; documentation of the occultation observations and associated calibrations; calculation of the occultation geometry for each event; establish prototype PDS templates. As discussed in our renewal proposal, submitted 8 June 1993, we have completed the first three tasks, and are working on the fourth. As an indication of our progress to date, we provide information about each of the data sets, their formats, the documentation, and the method used for reconstructing the occultation geometry.

  16. Dynamical systems analysis of fluid transport in time-periodic vortex ring flows

    NASA Astrophysics Data System (ADS)

    Shariff, Karim; Leonard, Anthony; Ferziger, Joel H.

    2006-04-01

    It is known that the stable and unstable manifolds of dynamical systems theory provide a powerful tool for understanding Lagrangian aspects of time-periodic flows. In this work we consider two time-periodic vortex ring flows. The first is a vortex ring with an elliptical core. The manifolds provide information about entrainment and detrainment of irrotational fluid into and out of the volume transported with the ring. The likeness of the manifolds with features observed in flow visualization experiments of turbulent vortex rings suggests that a similar process might be at play. However, what precise modes of unsteadiness are responsible for stirring in a turbulent vortex ring is left as an open question. The second situation is that of two leapfrogging rings. The unstable manifold shows striking agreement with even the fine features of smoke visualization photographs, suggesting that fluid elements in the vicinity of the manifold are drawn out along it and begin to reveal its structure. We suggest that interpretations of these photographs that argue for complex vorticity dynamics ought to be reconsidered. Recently, theoretical and computational tools have been developed to locate structures analogous to stable and unstable manifolds in aperiodic, or finite-time systems. The usefulness of these analogs is demonstrated, using vortex ring flows as an example, in the paper by Shadden, Dabiri, and Marsden [Phys. Fluids 18, 047105 (2006)].

  17. Manufacture of the ALS storage ring vacuum system

    NASA Astrophysics Data System (ADS)

    Kennedy, Kurt

    1991-08-01

    The Advanced Light Source (ALS) storage ring has a 4.9 meter magnetic radius and an antechamber type vacuum chamber. These two requirements makes conventional bent tube manufacturing techniques difficult. The ALS sector vacuum chambers have been made by machining two halves out of aluminum plate and welding at the mid plane. Each of these chambers have over 50 penetrations with metal sealed flanges and seven metal sealed poppet valves which use the chamber wall as the valve seat. The sector chambers are 10 meters long and some features in the chambers must be located to .25 mm. This paper describes how and how successfully these features have been achieved.

  18. Planetary Rings

    NASA Technical Reports Server (NTRS)

    Cuzzi, Jeffrey N.

    1994-01-01

    Just over two decades ago, Jim Pollack made a critical contribution to our understanding of planetary ring particle properties, and resolved a major apparent paradox between radar reflection and radio emission observations. At the time, particle properties were about all there were to study about planetary rings, and the fundamental questions were, why is Saturn the only planet with rings, how big are the particles, and what are they made of? Since then, we have received an avalanche of observations of planetary ring systems, both from spacecraft and from Earth. Meanwhile, we have seen steady progress in our understanding of the myriad ways in which gravity, fluid and statistical mechanics, and electromagnetism can combine to shape the distribution of the submicron-to-several-meter size particles which comprise ring systems into the complex webs of structure that we now know them to display. Insights gained from studies of these giant dynamical analogs have carried over into improved understanding of the formation of the planets themselves from particle disks, a subject very close to Jim's heart. The now-complete reconnaissance of the gas giant planets by spacecraft has revealed that ring systems are invariably found in association with families of regular satellites, and there is ark emerging perspective that they are not only physically but causally linked. There is also mounting evidence that many features or aspects of all planetary ring systems, if not the ring systems themselves, are considerably younger than the solar system

  19. Solar system history as recorded in the Saturnian ring structure

    NASA Technical Reports Server (NTRS)

    Alfven, H.

    1983-01-01

    Holberg's analysis of the Voyager Saturn photographs in reflected and transparent light, and occultation data of stars seen through the rings are discussed. A hyperfine structure, with 10,000 ringlets can be explained by the Baxter-Thompson negative diffusion. This gives the ringlets a stability which makes it possible to interpret them as fossils, which originated at cosmogonic times. It is shown that the bulk structure can be explained by the combined cosmogonic shadows of the satellites Mimas, Janus and the Shepherd satellites. This structure originated at the transition from the plasma phase to the planetesimal phase. The shadows are not simple void regions but exhibit a characteristic signature. Parts of the fine structure, explained by Holberg as resonances with satellites, are interpreted as cosmogonic shadow effects. However, there are a number of ringlets which can neither be explained by cosmogonic nor by resonance effects. Analysis of ring data can reconstruct the plasma-planetesimal transition with an accuracy of a few percent.

  20. Analysis of a Triple Star System Occulted By Saturn’s Rings

    NASA Astrophysics Data System (ADS)

    Bratcher, Allison; Colwell, J. E.; Bolin, B.

    2012-10-01

    On January 4, 2012, the Ultraviolet Imaging Spectrograph aboard the Cassini Spacecraft observed Saturn’s rings as they occulted the triple star system, Iota Orionis. Remarkably, the brightest star was occulted by the moon Prometheus, and we provide the timing information of first and last contact for navigation purposes and a chord across the moon. The large separation of the individual stars projected in the ring plane makes it possible to measure the profiles of narrow features in the rings as they were occulted by each of the three stars. This occultation thus provides a unique opportunity to measure short-scale longitudinal variations in narrow ringlets with stellar occultation data that usually provide only a single longitudinal sample. Iota Orionis has a low elevation angle (B=1.4 degrees) above the plane of the rings, enhancing the sensitivity of the occultation (by a factor of 1/sin(B)=41) to the optically thin regions of the rings such as the C Ring and the Cassini Division as well as faint ringlets in the Encke gap. We distinguished the three signals by creating a model triple star signal using data from another occultation. We were able to identify several faint, narrow ringlets, including two in the Encke gap, occulted by two of the three stars and more prominent ringlets, such as the Huygens ringlet, in all three stellar light curves. We present the equivalent widths of these ringlets in the data from this triple star system and limits on ring variability over the azimuthal separation of the stars that ranges from 6000 km at the inner C ring to 200 km at the outer A ring.

  1. Clumps and Temporal Changes in the Jovian Ring System as Viewed by New Horizons

    NASA Astrophysics Data System (ADS)

    Showalter, Mark R.; Cheng, A. F.; Weaver, H. A.; Stern, S. A.; Spencer, J. R.; Throop, H.; Birath, E. M.; Rose, D.; Moore, J. M.

    2007-10-01

    New Horizons obtained 400 ring images of the Jovian ring system using the Long Range Reconnaissance Imager (LORRI). This camera has a broad bandpass spanning wavelengths λ = 0.35 to 0.85 µm. The ring was imaged at phase angles 7°-159°. In addition, one sequence of near-IR spectra (λ = 1.25 to 2.5 µm) was obtained by the Linear Etalon Imaging Spectral Array (LEISA) for compositional studies. Two ring rotation movies during Jupiter approach were used to search for small moons embedded within the system. These bodies might serve as source bodies for the prevalent ring dust. No moons were detected down to a threshold of 500 m radius, suggesting a sharp cutoff in the population of inner Jovian moons below 8-km Adrastea. Although this search focused on the main Jovian ring, any 1-km moons from orbital radius r = 100,000 km to beyond the orbit of Amalthea (r = 181,000 km) should have been detected multiple times. More surprisingly, the ring revealed two clusters of tiny clumps, one pair and one set of three. These are definitively not moons because they have longitudinal extents of a few tenths of a degree. Separations between clumps are 2 to 4° but are not uniform. These clump families both orbit within a brightness peak just interior to the orbit of Adrastea, at r = 128,740 km. Their origin is unknown. They are not visible at high phase angles, indicating that they are composed primarily of larger "parent” bodies, not dust. They are definitely not related to a clump detected in Cassini images of the Jovian ring from December 2000, indicating that at least some ring clumps are transient. The large quadrant asymmetries reported in earlier images from Voyager and Galileo are completely absent in the new data.

  2. DESIGN AND DEVELOPMENT OF THE SNS RING VACUUM INSTRUMENTATION AND CONTROL SYSTEMS.

    SciTech Connect

    HSEUH,H.C.; SMART,L.A.; TANG,J.Y.

    2001-06-18

    BNL is undertaking the design, construction and commissioning of the Spallation Neutron Source (SNS) accumulator ring and the beam transport lines [l]. Ultrahigh vacuum of 10{sup {minus}9} Torr is required in the accumulator ring to minimize beam-gas ionization, a contributing factor to the e-p instability observed in a few high-intensity proton storage rings. All vacuum instrumentation must be capable of local and remote operation to achieve a reliable vacuum system, especially in this extremely high intensity accelerator. The design and development of the SNS ring vacuum instrumentation and control through the Experimental Physics and Industrial Control System (EPICS) distributed real-time software tools are presented.

  3. Photon antibunching and bunching in a ring-resonator waveguide quantum electrodynamics system.

    PubMed

    Chen, Zihao; Zhou, Yao; Shen, Jung-Tsung

    2016-07-15

    We numerically investigate the photonic state generation and its nonclassical correlations in a ring-resonator waveguide quantum electrodynamics system. Specifically, we discuss photon antibunching and bunching in various scenarios, including the imperfect resonator with backscattering and dissipations. Our numerical results indicate that an imperfect ring resonator with backscattering can enhance the quality of antibunching. In addition, we also identify the quantum photonic halo phenomenon in the photon scattering dynamics and the shoulder effect in the second-order correlation function.

  4. Ring retroreflector system consisting of cube-corner reflectors with special coating

    SciTech Connect

    Burmistrov, V B; Sadovnikov, M A; Sokolov, A L; Shargorodskiy, V D

    2013-09-30

    The ring retroreflector system (RS) consisting of cubecorner reflectors (CCRs) with a special coating of reflecting surfaces, intended for uniaxially Earth-oriented navigation satellites, is considered. The error of distance measurement caused by both the laser pulse delay in the CCR and its spatial position (CCR configuration) is studied. It is shown that the ring RS, formed by the CCR with a double-spot radiation pattern, allows the distance measurement error to be essentially reduced. (nanogradient dielectric coatings and metamaterials)

  5. Performance of a two mirror, four reflection, ring field imaging system

    SciTech Connect

    Sommargren, G.E.

    1995-01-25

    The surface figure of the individual mirrors of a two mirror, four reflection, ring field imaging system has been measured after each phase of the construction process: substrate fabrication, coating and potting. Contributions to the final system wavefront error and performance of the system in terms of the modulation transfer function and initial imaging tests are discussed.

  6. Plasticizer contamination from vacuum system O-rings in a quadrupole ion trap mass spectrometer.

    PubMed

    Verge, Kent M; Agnes, George R

    2002-08-01

    The outgassing of plasticizers from Buna-N and Viton o-rings under vacuum lead to undesired ion-molecule chemistry in an Electrospray Quadrupole Ion Trap Mass Spectrometer. In experiments with the helium bath gas pressure >1.2 mTorr, or whenever analyte ions were stored for >100 ms, extensive loss of analyte ions by proton transfer or adduction with o-ring plasticizers bis(2-ethylhexyl) phthalate and bis(2-ethylhexyl) adipate occurred. A temporary solution to this contamination problem was found to be overnight refluxing in hexane of all the o-rings in the vacuum system. This procedure alleviated this plasticizer contamination for approximately 100 hours of operation. These results, and those that lead to identification of the contamination as plasticizers outgassing from o-rings are described.

  7. Phase-locked servo system. [for synchronizing the rotation of slip ring assembly

    NASA Technical Reports Server (NTRS)

    Burdin, C. (Inventor)

    1974-01-01

    A phase lock servo system is described for synchronizing the rotation of a slip ring assembly with the rotation of an air bearing table so that a minimum of torque will be imparted through cables extending from the slip ring assembly to the air bearing table as such is rotated. The system includes two servo loops. The first servo loop includes a rate gyroscope carried on the air bearing table which generates a signal through a summing junction to be compared with a signal coming from a tachometer coupled to the slip ring assembly. The corrective signal is applied to a torque motor for rotating the slip ring assembly. The second servo loop includes a pair of photo detector cells which generate pulses responsive to the rotation of the air bearing table and slip ring assembly which are fed through a phase detector, and a variable gain amplifier to the summing junction circuit to provide a fine adjustment for rotating the slip ring assembly.

  8. Nature of the attractive interaction between proton acceptors and organic ring systems.

    PubMed

    Arras, Emmanuel; Seitsonen, Ari Paavo; Klappenberger, Florian; Barth, Johannes V

    2012-12-14

    Systematic ab initio calculations are combined with a deconvolution of electrostatic contributions to analyze the interplay between potential hydrogen bond acceptors and organic rings with C(sp(2))-H groups (benzene, pyridine and cyclopentadiene). A distinct anisotropic interaction between the ring systems and the electron lone pairs of cyanide, water and other acceptor species is revealed that favors the in-plane orientation of the proton acceptor group. In the attractive regime this interaction carries a pronounced electrostatic signature. By decomposing the electrostatic contribution into parts attributed to different subunits of the ring systems we demonstrate that a major proportion of the interaction energy gain is originating from the non-adjacent moieties, that are not in close contact with. This behavior holds equally for homocyclic, heterocyclic and non-aromatic rings but contrasts that of the ethyne molecule, taken as reference for a weak hydrogen bond donor clearly exhibiting the expected localized character. The ring interaction requires the presence of π-electron clouds and typically results in an interaction energy gain of 40 to 80 meV. Our findings suggest the proton acceptor-ring interaction as a new category of intermolecular non-covalent interactions.

  9. Capture, acceleration and bunching rf systems for the MEIC booster and storage rings

    SciTech Connect

    Wang, Shaoheng; Guo, Jiquan; Lin, Fanglei; Morozov, Vasiliy; Rimmer, Robert A.; Wang, Haipeng; Zhang, Yuhong

    2015-09-01

    The Medium-energy Electron Ion Collider (MEIC), proposed by Jefferson Lab, consists of a series of accelerators. The electron collider ring accepts electrons from CEBAF at energies from 3 to 12 GeV. Protons and ions are delivered to a booster and captured in a long bunch before being ramped and transferred to the ion collider ring. The ion collider ring accelerates a small number of long ion bunches to colliding energy before they are re-bunched into a high frequency train of very short bunches for colliding. Two sets of low frequency RF systems are needed for the long ion bunch energy ramping in the booster and ion collider ring. Another two sets of high frequency RF cavities are needed for re-bunching in the ion collider ring and compensating synchrotron radiation energy loss in the electron collider ring. The requirements from energy ramping, ion beam bunching, electron beam energy compensation, collective effects, beam loading and feedback capability, RF power capability, etc. are presented. The preliminary designs of these RF systems are presented. Concepts for the baseline cavity and RF station configurations are described, as well as some options that may allow more flexible injection and acceleration schemes.

  10. A pinger system for the Los Alamos Proton Storage Ring

    SciTech Connect

    Hardek, T.W.; Thiessen, H.A.

    1991-01-01

    Developers at the Proton Storage Ring have long desired a modulator and electrode combination capable of kicking the 800-MeV proton beam enough to conduct tune measurements with full intensity beams. At present this has been accomplished by reducing the voltage on one extraction kicker modulator and turning the other off. This method requires that all of the accumulated beam be lost on the walls of the vacuum chamber. In addition to tune measurements a more recent desire is to sweep out beam that may have leaked into the area between bunches. A four-meter electrode has been designed and constructed for the purpose. The design is flexible in that the electrode may be split in the center and rotated in order to provide vertical and horizontal electrodes each 2 meters long. In addition two solid-state pulse modulators that can provide 10kV in burst mode at up to 700 KHz have been purchased. This hardware and its intended use are described. 3 refs., 2 figs., 1 tab.

  11. Auto-production of biosurfactants reverses the coffee ring effect in a bacterial system

    NASA Astrophysics Data System (ADS)

    Sempels, Wouter; de Dier, Raf; Mizuno, Hideaki; Hofkens, Johan; Vermant, Jan

    2013-04-01

    The deposition of material at the edge of evaporating droplets, known as the ‘coffee ring effect’, is caused by a radially outward capillary flow. This phenomenon is common to a wide array of systems including colloidal and bacterial systems. The role of surfactants in counteracting these coffee ring depositions is related to the occurrence of local vortices known as Marangoni eddies. Here we show that these swirling flows are universal, and not only lead to a uniform deposition of colloids but also occur in living bacterial systems. Experiments on Pseudomonas aeruginosa suggest that the auto-production of biosurfactants has an essential role in creating a homogeneous deposition of the bacteria upon drying. Moreover, at biologically relevant conditions, intricate time-dependent flows are observed in addition to the vortex regime, which are also effective in reversing the coffee ring effect at even lower surfactant concentrations.

  12. Kinetics of ring formation

    NASA Astrophysics Data System (ADS)

    Ben-Naim, E.; Krapivsky, P. L.

    2011-06-01

    We study reversible polymerization of rings. In this stochastic process, two monomers bond and, as a consequence, two disjoint rings may merge into a compound ring or a single ring may split into two fragment rings. This aggregation-fragmentation process exhibits a percolation transition with a finite-ring phase in which all rings have microscopic length and a giant-ring phase where macroscopic rings account for a finite fraction of the entire mass. Interestingly, while the total mass of the giant rings is a deterministic quantity, their total number and their sizes are stochastic quantities. The size distribution of the macroscopic rings is universal, although the span of this distribution increases with time. Moreover, the average number of giant rings scales logarithmically with system size. We introduce a card-shuffling algorithm for efficient simulation of the ring formation process and we present numerical verification of the theoretical predictions.

  13. Shipboard Application of a Ring Structured Distributed Computing System.

    DTIC Science & Technology

    Considerable research is currently going on into the application of distributed computing systems. They appear particularly suitable for the...structured distributed computing system might be adapted to function in this environment. Included in this consideration are the feasibility of

  14. [A novel pyridazino-fused ring system: synthesis of pyridazino[3,4-b]diazepam].

    PubMed

    Károlyházy, L; Horváth, G; Mátyus, P

    2001-08-01

    As an analogue of pyridazino-fused ring systems with pharmacological activities, the novel pyridazinol[3,4-b][1,5]diazepine ring system was prepared. The synthetic pathway includes three steps from 4 5-(N-benzyl-N-3-hydroxypropyl)amino derivative which is easily available through nucleophilic substitution reaction of the known 4,5-dichloro-2-methyl-6-nitro-3(2H)-pyridazinone (2) with N-benzyl-N-(3-hydroxypropyl)amine. In the first step, compound 4 was treated with thionyl chloride to give the chloropropyl derivative 5. In the second step, a Bechamp reduction was carried out with Fe in acetic acid to obtain the amino compound 6, and finally the ring closure reaction of 6 was performed in N,N-dimethylformamide in the presence of potassium carbonate at 110 degrees C for 40 hours. In this way the bicyclic compound 7 could be isolated in 48% yield.

  15. Configuration maintaining control of three-body ring tethered system based on thrust compensation

    NASA Astrophysics Data System (ADS)

    Huang, Panfeng; Liu, Binbin; Zhang, Fan

    2016-06-01

    Space multi-tethered systems have shown broad prospects in remote observation missions. This paper mainly focuses on the dynamics and configuration maintaining control of space spinning three-body ring tethered system for such mission. Firstly, we establish the spinning dynamic model of the three-body ring tethered system considering the elasticity of the tether using Newton-Euler method, and then validate the suitability of this model by numerical simulation. Subsequently, LP (Likins-Pringle) initial equilibrium conditions for the tethered system are derived based on rigid body's equilibrium theory. Simulation results show that tether slack, snapping and interaction between the tethers exist in the three-body ring system, and its' configuration can not be maintained without control. Finally, a control strategy based on thrust compensation, namely thrust to simulate tether compression under LP initial equilibrium conditions is designed to solve the configuration maintaining control problem. Control effects are verified by numerical simulation compared with uncontrolled situation. Simulation results show that the configuration of the three-body ring tethered system could maintain under this active control strategy.

  16. Physical Properties of the Saturnian Ring System Inferred from Cassini VIMS Opposition Observations

    NASA Astrophysics Data System (ADS)

    Hapke, B.; Nelson, R. M.; Brown, R. H.; Spilker, L. J.; Smythe, W. D.; Kamp, L.; Boryta, M.; Leader, F.; Matson, D. L.; Edgington, S.; Nicholson, P. D.; Filacchione, G.; Clark, R. N.; Bibring, J.; Baines, K. H.; Buratti, B. J.; Bellucci, G.; Capaccioni, F.; Cerroni, P.; Combes, M.; Coradini, A.; Cruikshank, D. P.; Drossart, P.; Formisano, V.; Jaumann, R.; Langevin, Y.; McCord, T.; Menella, V.; Sicardy, B.

    2005-12-01

    Much can be learned about the nature of Saturn's ring particles and their regoliths by studying the wavelength dependence of their reflectance as a function of phase angle. At small phase angles the reflectance of the rings exhibits the opposition effect (OE) a significant increase in reflectance as phase angle approaches zero degrees. The wavelength dependence of the width and the peak of the OE are indicators of important physical properties of the regoliths of the ring particles such as particle size, particle shape, packing density and albedo. The Cassini VIMS multi spectral imaging spectrometer obtained low phase observations of the Saturnian ring system from 0.4-5.2 microns during 2005. These data clearly show a pronounced (OE). Cassini VIMS opposition surge data indicate a wavelength dependence of the OE that relates to the size and separation of the scattering centers on the surface of the ring particles. Laboratory studies and theoretical models of the OE relate the size and shape of the reflectance increase to physical properties of the medium (Nelson et al, 2002; Spilker et al. 1995; Hapke et al., 1993)). The OE arises from two processes, shadow hiding (SH) and coherent backscattering (CB). The SHOE is observed because shadows cast by the particulate grains on one another are eliminated as phase angle approaches zero degrees. The CBOE is due to constructive interference between light rays traveling in opposite paths through the medium as the path length decreases with decreasing phase angle. The VIMS data at 1.9 microns, where the rings are highly reflective, indicate a strong CBOE effect, however, at 2.1 microns, where the rings are very absorbing, the shape of the phase curve is consistent with SHOE. Hapke et al. 1993,Science, 260, 509-511 Nelson, R. M. et al., 2002. Planetary and Space Science, 50, 849-856 Spilker aka Horn, L.J et al., 1995. IAU Colloquium #150 This work done at JPL under contract with NASA

  17. Comments on the interaction between the F ring system and its new discovered objects

    NASA Astrophysics Data System (ADS)

    Giuliatti Winter, S. M.; Ferreira Gonsalves, M. A.; Winter, O.; Cardozo Mourao, D.

    2005-08-01

    The arrival of the Cassini spacecraft to the saturnian system brought a huge amount of data. Among them there is the discovery of three satellites close to the F ring (S/2004 S3, S/2004 S4 and S/2004 S6) and two tenuous rings, one close to the satellite Prometheus (R 2004/S2) and other coorbital to the satellite Atlas (R 2004/ S1). Before the inclusion of these new bodies, this region already had some unexplained features. The F ring presents strands, kinks and clumps probably related to the close satellites Prometheus and Pandora and embedded moonlets. In this work we analysed the behaviour of the ring particles strands disturbed by a sample of small objects varying in size and orbital elements. The new discovered objects is part of this sample of objects. As an example, we showed that an object of 10km in radius forms a gap in the outer strand. There are no scattered particles, the gap is formed by particles which collide with the object. We also analysed a sample of hypothetical objects lying in the F ring region taking into account the perturbation of Prometheus, Pandora and the oblateness of Saturn. This analysis is primarily performed using the secular perturbation theory. Then we computed the Lyapunov characteristic exponent for these objects. These results are presented for a range of semi major axes and eccentricities. By using numerical simulation we can verify that the perturbation of Prometheus on the new rings causes a variation only in R 2004/S2. This perturbation is enough to open a gap and scatter particles in the direction of the F ring region. Acknowledgements: SMGW thanks FUNDUNESP, OCW thanks FUNDUNESP and CNPq, MAFG and DCM thank CAPES for the financial support.

  18. The SLS Storage Ring Vertical Position Monitoring System

    SciTech Connect

    Zelenika, Sasa

    2004-05-12

    The goal of monitoring the vertical position of the SLS machine was achieved by employing a capacitive gauge-based Hydrostatic Leveling System (HLS). Although all the preliminary results showed that the aimed HLS micrometric range resolutions and accuracies have been reached, the long-time behavior of the system revealed considerable drifts. A satisfactory solution could eventually be reached only by adding to the working fluid a fungicide.

  19. A laser system for the TESLA photon collider based on an external ring resonator

    NASA Astrophysics Data System (ADS)

    Will, I.; Quast, T.; Redlin, H.; Sandner, W.

    2001-10-01

    We present a concept of a laser system for a photon collider at the TESLA linac. It is based on an external optical ring cavity which is pumped by a short-pulse laser. A detailed discussion of the geometry of the external cavity is given.

  20. Synthesis of Stereochemically and Skeletally Diverse Fused Ring Systems from Functionalized C-Glycosides

    PubMed Central

    Gerard, Baudouin; Dandapani, Sivaraman; Duvall, Jeremy R.; Fitzgerald, Mark E.; Kesavan, Sarathy; Lee, Maurice D.; Lowe, Jason T.; Marié, Jean-Charles; Pandya, Bhaumik A.; Suh, Byung-Chul; O’Shea, Morgan Welzel; Dombrowski, Michael; Hamann, Diane; Lemercier, Berenice; Murillo, Tiffanie; Akella, Lakshmi B.; Foley, Michael A.; Marcaurelle, Lisa A.

    2013-01-01

    A diversity-oriented synthesis (DOS) strategy was developed for the synthesis of stereochemically diverse fused-ring systems containing a pyran moiety. Each scaffold contains an amine and methyl ester for future diversification via amine capping and amide coupling. Scaffold diversity was evaluated in comparison to previously prepared scaffolds via a shape-based principal moments of inertia (PMI) analysis. PMID:23692141

  1. Tunable optical analog to electromagnetically induced transparency in graphene-ring resonators system

    PubMed Central

    Wang, Yonghua; Xue, Chenyang; Zhang, Zengxing; Zheng, Hua; Zhang, Wendong; Yan, Shubin

    2016-01-01

    The analogue of electromagnetically induced transparency in optical ways has shown great potential in optical delay and quantum-information technology due to its flexible design and easy implementation. The chief drawback for these devices is the bad tunability. Here we demonstrate a tunable optical transparency system formed by graphene-silicon microrings which could control the transparent window by electro-optical means. The device consists of cascaded coupled ring resonators and a graphene/graphene capacitor which integrated on one of the rings. By tuning the Fermi level of the graphene sheets, we can modulate the round-trip ring loss so that the transparency window can be dynamically tuned. The results provide a new method for the manipulation and transmission of light in highly integrated optical circuits and quantum information storage devices. PMID:27941895

  2. Tunable optical analog to electromagnetically induced transparency in graphene-ring resonators system

    NASA Astrophysics Data System (ADS)

    Wang, Yonghua; Xue, Chenyang; Zhang, Zengxing; Zheng, Hua; Zhang, Wendong; Yan, Shubin

    2016-12-01

    The analogue of electromagnetically induced transparency in optical ways has shown great potential in optical delay and quantum-information technology due to its flexible design and easy implementation. The chief drawback for these devices is the bad tunability. Here we demonstrate a tunable optical transparency system formed by graphene-silicon microrings which could control the transparent window by electro-optical means. The device consists of cascaded coupled ring resonators and a graphene/graphene capacitor which integrated on one of the rings. By tuning the Fermi level of the graphene sheets, we can modulate the round-trip ring loss so that the transparency window can be dynamically tuned. The results provide a new method for the manipulation and transmission of light in highly integrated optical circuits and quantum information storage devices.

  3. Fused-Ring Oxazolopyrrolopyridopyrimidine Systems with Gram-Negative Activity

    PubMed Central

    Chen, Yiyuan; Moloney, Jonathan G.; Christensen, Kirsten E.; Moloney, Mark G.

    2017-01-01

    Fused polyheterocyclic derivatives are available by annulation of a tetramate scaffold, and been shown to have antibacterial activity against a Gram-negative, but not a Gram-positive, bacterial strain. While the activity is not potent, these systems are structurally novel showing, in particular, a high level of polarity, and offer potential for the optimization of antibacterial activity. PMID:28098784

  4. Tissue culture system using a PANDA ring resonator and wavelength router for hydroponic plant.

    PubMed

    Kamoldilok, Surachart; Suwanpayak, Nathaporn; Suttirak, Saisudawan; Yupapin, Preecha P

    2012-06-01

    A novel system of nanofluidics trapping and delivery, which is known as a tissue culture system is proposed. By using the intense optical pulse(i.e., a soliton pulse) and a system constructed by a liquid core waveguide, the optical vortices (gradient optical fields/wells) can be generated, where the trapping tools in the same way as the optical tweezers in the PANDA ring resonator can be formed. By controlling the suitable parameters, the intense optical vortices can be generated within the PANDA ring resonator, in which the nanofluidics can be trapped and moved (transported) dynamically within the Tissue culture system(a wavelength router), which can be used for tissue culture and delivery in the hydroponic plant system.

  5. Photometric and spectroscopic evidence for a dense ring system around Centaur Chariklo

    NASA Astrophysics Data System (ADS)

    Duffard, R.; Pinilla-Alonso, N.; Ortiz, J. L.; Alvarez-Candal, A.; Sicardy, B.; Santos-Sanz, P.; Morales, N.; Colazo, C.; Fernández-Valenzuela, E.; Braga-Ribas, F.

    2014-08-01

    Context. A stellar occultation observed on 3rd June 2013 revealed the presence of two dense and narrow rings separated by a small gap around the Centaur object (10 199) Chariklo. The composition of these rings is not known. We suspect that water ice is present in the rings, as is the case for Saturn and other rings around the giant planets. Aims: In this work, we aim to determine if the variability in the absolute magnitude of Chariklo and the temporal variation of the spectral ice feature, even when it disappeared in 2007, can be explained by an icy ring system whose aspect angle changes with time. Methods: We explained the variations on the absolute magnitude of Chariklo and its ring by modeling the light reflected by a system as the one described above. Using X-shooter at VLT, we obtained a new reflectance spectra. We compared this new set of data with the ones available in the literature. We showed how the water ice feature is visible in 2013 in accordance with the ring configuration, which had an opening angle of nearly 34° in 2013. Finally, we also used models of light scattering to fit the visible and near-infrared spectra that shows different characteristics to obtain information on the composition of Chariklo and its rings. Results: We showed that absolute photometry of Chariklo from the literature and new photometric data that we obtained in 2013 can be explained by a ring of particles whose opening angle changes as a function of time. We used the two possible pole solutions for the ring system and found that only one of them, α = 151.30 ± 0.5, δ = 41.48 ± 0.2° (λ = 137.9 ± 0.5, β = 27.7 ± 0.2°), provides the right variation of the aspect angle with time to explain the photometry, whereas the other possible pole solution fails to explain the photometry. From spectral modeling, we derived the composition of the Chariklo surface and that of the rings using the result on the pole solution. Chariklo surface is composed with about 60% of amorphous

  6. An innovative seismic bracing system based on a superelastic shape memory alloy ring

    NASA Astrophysics Data System (ADS)

    Gao, Nan; Jeon, Jong-Su; Hodgson, Darel E.; DesRoches, Reginald

    2016-05-01

    Shape memory alloys (SMAs) have great potential in seismic applications because of their remarkable superelasticity. Seismic bracing systems based on SMAs can mitigate the damage caused by earthquakes. The current study investigates a bracing system based on an SMA ring which is capable of both re-centering and energy dissipation. This lateral force resisting system is a cross-braced system consisting of an SMA ring and four tension-only cable assemblies, which can be applied to both new construction and seismic retrofit. The performance of this bracing system is examined through a quasi-static cyclic loading test and finite element (FE) analysis. This paper describes the experimental design in detail, discusses the experimental results, compares the performance with other bracing systems based on SMAs, and presents an Abaqus FE model calibrated on the basis of experimental results to simulate the superelastic behavior of the SMA ring. The experimental results indicate that the seismic performance of this system is promising in terms of damping and re-centering. The FE model can be used in the simulation of building structures using the proposed bracing system.

  7. Stability Analysis of a Turbocharger Rotor System Supported on Floating Ring Bearings

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Shi, Z. Q.; Zhen, D.; Gu, F. S.; Ball, A. D.

    2012-05-01

    The stability of a turbocharger rotor is governed by the coupling of rotor dynamics and fluid dynamics because the high speed rotor system is supported on a pair of hydrodynamic floating ring bearings which comprise of inner and outer fluid films in series. In order to investigate the stability, this paper has developed a finite element model of the rotor system with consideration of such exciting forces as rotor imbalance, hydrodynamic fluid forces, lubricant feed pressure and dead weight. The dimensionless analytical expression of nonlinear oil film forces in floating ring bearings have been derived on the basis of short bearing theory. Based on numerical simulation, the effects of rotor imbalance, lubricant viscosity, lubricant feed pressure and bearing clearances on the stability of turbocharger rotor system have been studied. The disciplines of the stability of two films and dynamic performances of rotor system have been provided.

  8. Dissipative effects on the mu and nu dust particles of Uranus' secondary ring system

    NASA Astrophysics Data System (ADS)

    Sfair, Rafael; Giuliatti Winter, Silvia Maria

    In 2006, an outer ring-moon system composed by the satellites Portia, Rosalind, Puck, and Mab, and two tenuous rings µ and ν, was discovered around Uranus by Showalter Lissauer (2006). We present the results of numerical simulations of an ensemble of micrometric particles of both rings disturbed by a combination of the solar radiation pressure force, the gravitational interaction with the satellites, and the planetary gravity modified by the oblateness. Our results show that the Poynting-Robertson drag component alone is responsible for a de-crease of the semimajor axis in a time scale of 105 to 106 years. In a shorter time scale, the oscillation of the eccentricity, caused by the radiation pressure component, is much more im-portant to the orbital evolution of the particle, even though the amplitude of oscillation is mitigated by the inclusion of the planetary oblateness. The combination of these effects with the gravitational interaction of the satellites result in close encounters between the particles and the satellites, leading the particles to move inward and outward within the ring region, and eventually colliding with the satellites. The percentage of collisions varies between 12% and 94% according to the size of the particle. All collisions with Puck, Portia and Rosalind have the value of impact velocity comparable to the escape velocity, which the most likely result is the deposition of material onto the surface of the satellite. In the other hand, the impact velocity with Mab exceeds the scape velocity of the satellite, so these collisions are energetic enough to eject material and supply material to the µ ring. This mechanics of dust production can also be applied to collisions with macroscopic bodies that my inhabit within the µ and ν rings.

  9. Pressurized balanced sealing system for use on the ring-liner interface of a coal fired diesel engine

    SciTech Connect

    Leonard, G.L.

    1989-03-14

    A system for minimizing a wear to a reciprocating internal combustion engine is described, consisting of a cylinder having a wall and a combustion chamber within the cylinder; a piston movable in a stroke within the cylinder between a top dead center position and a bottom dead center position, the piston having first and second ends, the first end being adjacent to the combustion chamber and the second end being remote from the combustion chamber; first, second, and third piston rings extending around the piston, the second piston ring being positioned between the first and the third piston rings; a ring pack area on the piston between the first piston ring and the second piston ring; a lubricant blowby area between the second piston ring and the third piston ring; and a pump communicating with an inlet in the wall such that the lubricant blowby area registers with the inlet during at least part of the stroke of the piston, the pump having an outlet in the wall such that the ring pack area registers with the outlet during at least part of the stroke of the piston, the pump operable to draw lubricant from the lubricant blowby area and provide lubricant to the ring pack area.

  10. Formation of regular satellites from ancient massive rings in the solar system.

    PubMed

    Crida, A; Charnoz, S

    2012-11-30

    When a planetary tidal disk--like Saturn's rings--spreads beyond the Roche radius (inside which planetary tides prevent aggregation), satellites form and migrate away. Here, we show that most regular satellites in the solar system probably formed in this way. According to our analytical model, when the spreading is slow, a retinue of satellites appear with masses increasing with distance to the Roche radius, in excellent agreement with Saturn's, Uranus', and Neptune's satellite systems. This suggests that Uranus and Neptune used to have massive rings that disappeared to give birth to most of their regular satellites. When the spreading is fast, only one large satellite forms, as was the case for Pluto and Earth. This conceptually bridges the gap between terrestrial and giant planet systems.

  11. Controllable multiple-quantum transitions in a T-shaped small quantum dot-ring system

    NASA Astrophysics Data System (ADS)

    Chen, Xiongwen; Chen, Baoju; Song, Kehui; Zhou, Guanghui

    2016-05-01

    Based on the tight-binding model and the slave boson mean field approximation, we investigate the electron transport properties in a small quantum dot (QD)-ring system. Namely, a strongly correlated QD not only attaches directly to two normal metallic electrodes, but also forms a magnetic control Aharonov-Bohm quantum ring with a few noninteracting QDs. We show that the parity effect, the Kondo effect, and the multiple Fano effects coexist in our system. Moreover, the parities, defined by the odd- and even-numbered energy levels in this system, can be switched by adjusting magnetic flux phase ϕ located at the center of the quantum ring, which induces multiple controllable Fano-interference energy pathways. Therefore, the constructive and destructive multi-Fano interference transition, the Kondo and Fano resonance transition at the Fermi level, the Fano resonance and ani-resonance transition are realized in the even parity system. They can also be observed in the odd parity system when one adjusts the phase ϕ and the gate voltage Vg applied to the noninteracting QDs. The multi-quantum transitions determine some interesting transport properties such as the current switch and its multi-flatsteps, the differential conductance switch at zero bias voltage and its oscillation or quantization at the low bias voltage. These results may be useful for the observation of multiple quantum effect interplays experimentally and the design of controllable QD-based device.

  12. A new systematic calibration method of ring laser gyroscope inertial navigation system

    NASA Astrophysics Data System (ADS)

    Wei, Guo; Gao, Chunfeng; Wang, Qi; Wang, Qun; Xiong, Zhenyu; Long, Xingwu

    2016-10-01

    Inertial navigation system has been the core component of both military and civil navigation systems. Before the INS is put into application, it is supposed to be calibrated in the laboratory in order to compensate repeatability error caused by manufacturing. Discrete calibration method cannot fulfill requirements of high-accurate calibration of the mechanically dithered ring laser gyroscope navigation system with shock absorbers. This paper has analyzed theories of error inspiration and separation in detail and presented a new systematic calibration method for ring laser gyroscope inertial navigation system. Error models and equations of calibrated Inertial Measurement Unit are given. Then proper rotation arrangement orders are depicted in order to establish the linear relationships between the change of velocity errors and calibrated parameter errors. Experiments have been set up to compare the systematic errors calculated by filtering calibration result with those obtained by discrete calibration result. The largest position error and velocity error of filtering calibration result are only 0.18 miles and 0.26m/s compared with 2 miles and 1.46m/s of discrete calibration result. These results have validated the new systematic calibration method and proved its importance for optimal design and accuracy improvement of calibration of mechanically dithered ring laser gyroscope inertial navigation system.

  13. COMPUTATIONAL BEAM DYNAMICS STUDIES FOR IMPROVING THE RING INJECTION AND EXTRACTION SYSTEMS IN SNS

    SciTech Connect

    Holmes, Jeffrey A; Cousineau, Sarah M; Plum, Michael A; Wang, Jian-Guang

    2008-01-01

    The ring injection and extraction systems must function as designed in order for the Spallation Neutron Source (SNS) to achieve its specified performance. In commissioning and early operations we have encountered problems that have been traced to these systems. We experienced high beam losses in and around the injection dump, the rectification of which has necessitated ongoing study and development by a multidisciplinary team. Results already include a number of enhancements of existing features and the addition of new elements and diagnostics. The problem in the extraction region stems from tilted beam distributions observed in the ring-to-target beam transport line (RTBT) and on the target, thus complicating the control of the beam-on-target distribution. This indicates the inadvertent introduction of x-y beam coupling somewhere upstream of the RTBT. The present paper describes computational studies, using the ORBIT Code, addressed at the detailed understanding and solution of these problems.

  14. Overall design concepts for the APS storage ring machine protection system

    SciTech Connect

    Lumpkin, A.; Fuja, R.; Votaw, A.; Wang, X.; Shu, D.; Stepp, J.; Arnold, N.; Nawrocki, G.; Decker, G.; Chung, Y.

    1995-07-01

    The basic design and status of the machine protection system for the Advanced Photon Source (APS) storage ring are discussed. The machine is passively safe to the bending magnet sources, but the high power of the insertion devices requires missteering conditions to be identified and the beam aborted in less than one millisecond. The basic aspects of waterflow, temperature, beam position, etc. monitoring are addressed. Initial commissioning of subsystems and sensors is statused.

  15. On the Relation between Stable Matrix Fraction Factorizations and Regulable Realizations of Linear Systems Over Rings,

    DTIC Science & Technology

    1981-01-13

    rings usual theory in which coefficients of x(t) and u(t) are approach is based on generalizations of state space tech- constant, but generalized to...AFOSR-WO) 196. P. P. Khargonekar is with the Center for Mathematical System Theory control-theoretic problems (output regulation. tracking, and and the...denote the minimal possible cardinafity of a set our approach here and that in recent transfer matrix design of generators for the module X. /All "modules

  16. Fluorous Synthesis of Hydantoin-, Piperazinedione-, and Benzodiazepinedione-Fused Tricyclic and Tetracyclic Ring Systems.

    PubMed

    Zhang, Wei; Lu, Yimin; Chen, Christine Hiu-Tung; Curran, Dennis P; Geib, Steven

    2006-01-01

    Fluorous proline derivatives generated from one-pot, three-component [3+2] cycloaddition of azomethine ylides are employed for different post-condensation reactions to form hydantoin-, piperazinedione-, and benzodiazepinedione-fused tricyclic and tetracyclic ring systems. The high synthetic efficiency is achieved by conducting fast microwave reactions and easy fluorous-solid phase extractions for reaction mixture purifications. Methods developed for these novel drug-like heterocyclic compounds can be applied to diversity-oriented library synthesis.

  17. Fluorous Synthesis of Hydantoin-, Piperazinedione-, and Benzodiazepinedione-Fused Tricyclic and Tetracyclic Ring Systems

    PubMed Central

    Zhang, Wei; Lu, Yimin; Chen, Christine Hiu-Tung; Curran, Dennis P.; Geib, Steven

    2007-01-01

    Fluorous proline derivatives generated from one-pot, three-component [3+2] cycloaddition of azomethine ylides are employed for different post-condensation reactions to form hydantoin-, piperazinedione-, and benzodiazepinedione-fused tricyclic and tetracyclic ring systems. The high synthetic efficiency is achieved by conducting fast microwave reactions and easy fluorous-solid phase extractions for reaction mixture purifications. Methods developed for these novel drug-like heterocyclic compounds can be applied to diversity-oriented library synthesis. PMID:18542714

  18. Nonadiabatic charge pumping by oscillating potentials in one dimension: Results for infinite system and finite ring

    NASA Astrophysics Data System (ADS)

    Soori, Abhiram; Sen, Diptiman

    2010-09-01

    We study charge pumping when a combination of static potentials and potentials oscillating with a time period T is applied in a one-dimensional system of noninteracting electrons. We consider both an infinite system using the Dirac equation in the continuum approximation and a periodic ring with a finite number of sites using the tight-binding model. The infinite system is taken to be coupled to reservoirs on the two sides which are at the same chemical potential and temperature. We consider a model in which oscillating potentials help the electrons to access a transmission resonance produced by the static potentials and show that nonadiabatic pumping violates the simple sinϕ rule which is obeyed by adiabatic two-site pumping. For the ring, we do not introduce any reservoirs, and we present a method for calculating the current averaged over an infinite time using the time evolution operator U(T) assuming a purely Hamiltonian evolution. We analytically show that the averaged current is zero if the Hamiltonian is real and time-reversal invariant. Numerical studies indicate another interesting result, namely, that the integrated current is zero for any time dependence of the potential if it is applied to only one site. Finally we study the effects of pumping at two sites on a ring at resonant and nonresonant frequencies, and show that the pumped current has different dependences on the pumping amplitude in the two cases.

  19. Constraints on the size and dynamics of the J1407b ring system

    NASA Astrophysics Data System (ADS)

    Rieder, Steven; Kenworthy, Matthew A.

    2016-11-01

    Context. J1407 (1SWASP J140747.93-394542.6 in full) is a young star in the Scorpius-Centaurus OB association that underwent a series of complex eclipses over 56 days in 2007. To explain these, it was hypothesised that a secondary substellar companion, J1407b, has a giant ring system filling a large fraction of the Hill sphere, causing the eclipses. Observations have not successfully detected J1407b, but do rule out circular orbits for the companion around the primary star. Aims: We test to what degree the ring model of J1407b could survive in an eccentric orbit required to fit the observations. Methods: We run N-body simulations under the AMUSE framework to test the stability of Hill radius-filling systems where the companion is on an eccentric orbit. Results: We strongly rule out prograde ring systems and find that a secondary of 60 to 100 MJup with an 11 yr orbital period and retrograde orbiting material can survive for at least 104 orbits and produce eclipses with similar durations as the observed one.

  20. Conditioning of the vacuum system of the TPS storage ring without baking in situ

    NASA Astrophysics Data System (ADS)

    Chan, C. K.; Chang, C. C.; Shueh, C.; Yang, I. C.; Wu, L. H.; Chen, B. Y.; Cheng, C. M.; Huang, Y. T.; Chuang, J. Y.; Cheng, Y. T.; Hsiao, Y. M.; Sheng, Albert

    2017-04-01

    To shorten the machine downtime, a maintenance procedure without baking in situ has been developed and applied to maintain and to upgrade the vacuum system of the TPS storage ring. The data of photon-stimulated desorption (PSD) reveal no obvious discrepancy between baking and not baking the vacuum system in situ. A beam-conditioning dose of extent only 11.8 A h is required to recover quickly the dynamic pressure of an unbaked vacuum system to its pre-intervention value according to the TPS maintenance experience.

  1. Monitor and control systems for the SLD Cherenkov Ring Imaging Detector

    SciTech Connect

    Antilogus, P.; Aston, D.; Bienz, T.; Bird, F.; Dasu, S.; Dunwoodie, W.; Fernandez, F.; Hallewell, G.; Kawahara, H.; Korff, P.; Kwon, Y.; Leith, D.; Muller, D.; Nagamine, T.; Pavel, T.; Rabinowitz, L.; Ratcliff, B.; Rensing, P.; Schultz, D.; Shapiro, S.; Simopoulos, C.; Solodov, E.; Toge, N.; Va'Vra, J.; Williams, S.; Whitaker, J.; Wilson, R.J.; Bean, A.; Caldwell, D.; Duboscq, J.; Huber, J.; Lu, A.; McHugh, S.; Mathys, L.; Morriso

    1989-10-01

    To help ensure the stable long-term operation of a Cherenkov Ring Detector at high efficiency, a comprehensive monitor and control system is being developed. This system will continuously monitor and maintain the correct operating temperatures, and will provide an on-line monitor and maintain the correct operating temperatures, and will provide an on-line monitor of the pressures, flows, mixing, and purity of the various fluids. In addition the velocities and trajectories of Cherenkov photoelectrons drifting within the imaging chambers will be measured using a pulsed uv lamp and a fiberoptic light injection system. 9 refs., 6 figs.

  2. Commissioning and Early Operation Experience of the NSLS-II Storage Ring RF System

    SciTech Connect

    Gao, F.; Rose, J.; Cupolo, J.; Dilgen, T.; Rose, B.; Gash, W.; Ravindranath, V.; Yeddulla, M.; Papu, J.; Davila, P.; Holub, B.; Tagger, J.; Sikora, R.; Ramirez, G.; Kulpin, J.

    2015-05-03

    The National Synchrotron Light Source II (NSLS-II) is a 3 GeV electron X-ray user facility commissioned in 2014. The storage ring RF system, essential for replenishing energy loss per turn of the electrons, consists of digital low level RF controllers, 310 kW CW klystron transmitters, CESR-B type superconducting cavities, as well as a supporting cryogenic system. Here we will report on RF commissioning and early operation experience of the system for beam current up to 200mA.

  3. A search for minor bodies in the Jovian tenuous ring system

    NASA Astrophysics Data System (ADS)

    Malinnikova Bang, A.; Joergensen, J. L.; Connerney, J. E.; Benn, M.; Denver, T.; Oliversen, R. J.; Lawton, P.

    2013-12-01

    The magnetometer experiment on the Juno spacecraft, is equipped with four fully autonomous star trackers, which apart from delivering highly accurate attitude information for the magnetometer sensors, and the inherent imaging capabilities of a low light camera system, also can detect and track luminous objects that exhibit an apparent motion rate relative to the background. The Juno magnetometer star trackers are pointed 13deg of the spacecraft anti-spin vector, each having a field of view of 13 by 18 degrees and operated at 4Hz. As the spacecraft spin, each camera will cover an annulus shaped disk with an inner radius of 7.5 degrees, and an outer radius of 20.5deg. When in science orbit, the Juno trajectory near peri-jove, will result in the anti-spin vector scanning across the tenuous rings. The combination of this scanning motion with the rotation of the camera field of view results in a near perfect opportunity to detect and track minor bodies in the inner part of the rings. The operations of this mode, is first tested in flight during the Juno Earth Flyby 9th October 2013, where the Moon is used as a known target. We present a few results of this test, and based on scale laws we will discuss the systems capability of detecting minor bodies in the Jovian ring system in terms of distance, velocity, albedo and range. Also, because the magnetometer star trackers are offset from the spin axis, the distance to a detected object can be derived by simple triangulation of the apparent direction as observed before, under and after passage under the rings. We discuss how this technique may be used to determine the orbit, size and albedo, of minor bodies thus detected and tracked.

  4. Improved temperature regulation of process water systems for the APS storage ring.

    SciTech Connect

    Putnam, C.; Dortwegt, R.

    2002-10-10

    Beam stability and operational reliability of critical mechanical systems are key performance issues for synchrotron accelerators such as the Advanced Photon Source (APS). Stability is influenced by temperature fluctuations of the process water (PW) used for cooling and/or temperature conditioning storage ring (SR) components such as vacuum chambers, magnets, absorbers, etc. Operational reliability is crucial in maintaining facility beam operations and remaining within downtime ''budgets.'' Water systems for the APS storage ring were originally provided with a distributive control system (DCS) capable of regulation to {+-}1.0 F, as specified by facility design requirements. After several years of operation, a particular mode of component mortality indicated a need for upgrade of the temperature control system. The upgrade that was implemented was chosen for both improved component reliability and temperature stability (now on the order of {+-}0.2 F for copper components and {+-}0.05 F for aluminum components). The design employs a network of programmable logic controllers (PLCs) for temperature control that functions under supervision of the existing DCS. The human-machine interface (HMI) of the PLC system employs RSView32 software. The PLC system also interfaces with the EPICS accelerator control system to provide monitoring of temperature control parameters. Eventual supervision of the PLC system by EPICS is possible with this design.

  5. James Webb Space Telescope Observations of Stellar Occultations by Solar System Bodies and Rings

    NASA Technical Reports Server (NTRS)

    Santos-Sanz, P.; French, R. G.; Pinilla-Alonso, N.; Stansberry, J.; Lin, Z-Y.; Zhang, Z-W.; Vilenius, E.; Mueller, Th.; Ortiz, J. L.; Braga-Ribas, F.; Bosh, A.; Duffard, R.; Lellouch, E.; Tancredi, G.; Young, Leslie; Milam, Stefanie N.

    2016-01-01

    In this paper, we investigate the opportunities provided by the James Webb Space Telescope (JWST) for significant scientific advances in the study of Solar System bodies and rings using stellar occultations. The strengths and weaknesses of the stellar occultation technique are evaluated in light of JWST's unique capabilities. We identify several possible JWST occultation events by minor bodies and rings and evaluate their potential scientific value. These predictions depend critically on accurate a priori knowledge of the orbit of JWST near the Sun–Earth Lagrange point 2 (L2). We also explore the possibility of serendipitous stellar occultations by very small minor bodies as a byproduct of other JWST observing programs. Finally, to optimize the potential scientific return of stellar occultation observations, we identify several characteristics of JWST's orbit and instrumentation that should be taken into account during JWST's development.

  6. The fluid systems for the SLD Cherenkov ring imaging detector. [01

    SciTech Connect

    Abe, K.; Hasegawa, K.; Hasegawa, Y.; Iwasaki, Y.; Suekane, F.; Yuta, H. . Dept. of Physics); Antilogus, P.; Aston, D.; Bienz, T.; Bird, F.; Dasu, S.; Dolinsky, S.; Dunwoodie, W.; Hallewell, G.; Kawahara, H.; Kwon, Y.; Leith, D.W.G.S.; McCulloch, M.; McShurley, D.; Mueller, G.; Muller, D.; Nagamine, T.; Pavel, T.J.; Peterson, H.; Ratcliff, B.; Reif, R.; Rensing, P.; Schultz, D.; Shapiro, S.; Shaw,

    1992-10-01

    We describe the design and operation of the fluid delivery, monitor and control systems for the SLD barrel Cherenkov Ring Imaging Detector (CRID). The systems deliver drift gas (C[sub 2]H[sub 6] + TMAE), radiator gas (C[sub 5]F[sub 12] + N[sub 2]) and radiator liquid (C[sub 6]F[sub 14]). Measured critical quantities such as electron lifetime in the drift gas and ultra-violet (UV) transparencies of the radiator fluids, together with the operational experience, are also reported.

  7. Surfaces, atmospheres and magnetospheres of the outer planets and their satellites and ring systems: Part X

    NASA Astrophysics Data System (ADS)

    Coustenis, A.; Atreya, S.; Castillo, J.; Coll, P.; Mueller-Wodarg, I.; Spilker, L.

    2014-12-01

    This issue contains research work presented during the past year in sessions organized at several international meetings and congresses (such as those of the European Geosciences Union (EGU), the Asia Oceania Geosciences Society (AOGS), the European Planetary Science Congress (EPSC) and others) and focusing on recent observations and models of the atmospheres, magnetospheres and surfaces of the giant planets and their satellites, as well as on their ring systems. Particular attention was devoted this time to the proposals for exploration of the Solar System by spacecraft and probes submitted during the ESA call for science themes for the L2 and L3 missions in 2013.

  8. Simulation and analysis of rf feedback systems on the SLC damping rings

    SciTech Connect

    Minty, M.; Himel, T.; Krejcik, P.; Siemann, R.H.; Tighe, R.

    1993-09-01

    The rf system of the SLC Damping Rings has evolved since tighter tolerances on beam stability are encountered as beam intensities are increased. There are now many feedback systems controlling the phase and amplitude of the rf, the phase of the beam, and the tune of the cavity. The bandwidths of the feedback loops range from several MHz to compensate for beam loading to a few Hz for the cavity tuners. To improve our understanding of the interaction of these loops and verify the expected behavior, we have simulated their behavior using computer models. A description of the models and the first results are discussed.

  9. Ballistic transport in planetary ring systems due to particle erosion mechanisms. I - Theory, numerical methods, and illustrative examples

    NASA Technical Reports Server (NTRS)

    Durisen, Richard H.; Murphy, Brian W.; Cramer, Nichael Lynn; Cuzzi, Jeffrey N.; Mullikin, Thomas L.

    1989-01-01

    Ballistic transport, defined as the net radial transport of mass and angular momentum due to exchanges of meteoroid hypersonic-impact ejecta by neighboring planetary ring regions on time-scales orders-of-magnitude shorter than the age of the solar system, is presently considered as a problem in mathematical physics. The preliminary results of a numerical scheme for following the combined effects of ballistic transport and viscous diffusion demonstrate that ballistic transport generates structure near sharp edges already present in the ring-mass distribution; the entire ring system ultimately develops an undulatory structure whose length scale is typically of the order of the radial excursion of the impact ejecta.

  10. The Spectral Classes of the Saturnian System Ices: Rings and Satellites Observations by Cassini-VIMS

    NASA Astrophysics Data System (ADS)

    Filacchione, G.; Capaccioni, F.; Tosi, F.; Coradini, A.; Cerroni, P.; Clark, R. N.; Cuzzi, J. N.; Nicholson, P. D.; Buratti, B. J.; Brown, R. H.; Cruikshank, D. P.; Jaumann, R.; Hedman, M. M.

    2008-12-01

    The entire population of the Saturnian system ices was investigated by VIMS (Visual and Infrared Mapping Spectrometer) experiment on board Cassini spacecraft. By the end of the nominal mission a very large dataset of hyperspectral data had been collected in the spectral range 0.35-5.0 micron, which includes the regular satellites (Mimas, Enceladus, Tethys, Dione, Rhea, Hyperion, Iapetus, Phoebe), minor moons (Atlas, Prometheus, Pandora, Janus, Epimetheus, Telesto, Calypso) and rings. In this work we present an analysis of spectrophotometric indicators selected to describe the properties of the ices (I/F continuum levels, visible spectral slopes, band depths and positions), and which were retrieved from about 1500 full-disk observations of satellites as well as from mosaics of the main rings (A, B, C, CD, F) sampled with a resolution of 125 km/pixel along the radial axis. This comparative method allows us to highlight the spectral differences in this population of objects orbiting in the Saturnian system. In particular we have retrieved the distribution of the water ice abundance, which varies between the almost pure icy surfaces of Enceladus and Calypso to the carbon dioxide- and organic-rich Hyperion, Iapetus and Phoebe. Noteworthy is that a significant dichotomy is observed between the two co-orbital moons Epimetheus and Janus, possibly indicating a different origin and evolutionary process: while the first shows a very red visible spectrum (similar to Hyperion), the second has more neutral visible colors, making it a very peculiar object in the Saturnian system. Rings have very peculiar spectral differences when compared with the icy satellites: in the visible range their spectra are characterized by a spectral knee at bluer wavelengths (at about 520 nm compared to 550 nm on satellites); in the infrared range the 1.5-2.0 micron water ice band depths are in general deeper across the A and B rings, indicative of a larger fraction of pure water ice in comparison to

  11. Saturn's seasonal winds and temperature: The effect of the ring system on the troposphere and stratosphere

    NASA Astrophysics Data System (ADS)

    Barnet, Christopher Dwight

    The radiative properties of Saturn's rings (insolation shadowing, insolation scattering, and thermal emission) were incorporated into a seasonal, zonally-averaged, radiative-dynamical model to investigate the magnitude of small seasonal fluctuations in the troposphere and stratosphere of Saturn. Although the radiative time constant is large in Saturn's troposphere and stratosphere, the rings induce significant latitudinal insolation gradients resulting in potential disturbances in the upper stratosphere. The results of the model are compared to the Pioneer and Voyager Radio Sub-System (RSS) vertical temperature profile measurements and to the Voyager Infrared Interferometric Spectrometer (IRIS) latitudinal temperature profile measurements. In the upper stratosphere (1 to 30 mBar) the heating is dominated by methane and the model can be directly compared to the Voyager data. Below the temperature minimum the radiative time constant is sufficiently long to strongly dampen seasonal variations, however, the temperature excursions seen in the IRIS data are significantly larger than those predicted by the radiative model. The thermal effects of the strong Saturnian zonal winds are simulated with a first-order dynamical model to provide some insight into the lower boundary conditions. The remaining differences between the model and the Voyager IRIS data-sets are used to estimate the quantity of aerosol required near the tropopause region. The magnitudes of the wind and temperature perturbations, caused by the radiative effects of Saturn's rings, are discussed in the context of the future Hubble Space Telescope and the planned Cassini Saturnian Orbiter missions.

  12. A Performance Comparison of Tree and Ring Topologies in Distributed System

    SciTech Connect

    Huang, Min

    2004-01-01

    A distributed system is a collection of computers that are connected via a communication network. Distributed systems have become commonplace due to the wide availability of low-cost, high performance computers and network devices. However, the management infrastructure often does not scale well when distributed systems get very large. Some of the considerations in building a distributed system are the choice of the network topology and the method used to construct the distributed system so as to optimize the scalability and reliability of the system, lower the cost of linking nodes together and minimize the message delay in transmission, and simplify system resource management. We have developed a new distributed management system that is able to handle the dynamic increase of system size, detect and recover the unexpected failure of system services, and manage system resources. The topologies used in the system are the tree-structured network and the ring-structured network. This thesis presents the research background, system components, design, implementation, experiment results and the conclusions of our work. The thesis is organized as follows: the research background is presented in chapter 1. Chapter 2 describes the system components, including the different node types and different connection types used in the system. In chapter 3, we describe the message types and message formats in the system. We discuss the system design and implementation in chapter 4. In chapter 5, we present the test environment and results, Finally, we conclude with a summary and describe our future work in chapter 6.

  13. ALMA unveils rings and gaps in the protoplanetary system HD 169142: signatures of two giant protoplanets

    NASA Astrophysics Data System (ADS)

    Fedele, D.; Carney, M.; Hogerheijde, M. R.; Walsh, C.; Miotello, A.; Klaassen, P.; Bruderer, S.; Henning, Th.; van Dishoeck, E. F.

    2017-04-01

    The protoplanetary system HD 169142 is one of the few cases where a potential candidate protoplanet has recently been detected by direct imaging in the near-infrared. To study the interaction between the protoplanet and the disk itself, observations of the gas and dust surface density structure are needed. This paper reports new ALMA observations of the dust continuum at 1.3 mm, 12CO, 13CO, and C18O J = 2-1 emission from the system HD 169142 (which is observed almost face-on) at an angular resolution of 0.3 arcsec × 0.2 arcsec ( 35 × 20 au). The dust continuum emission reveals a double-ring structure with an inner ring between 0.17 arcsec{-0.28 arcsec} ( 20-35 au) and an outer ring between 0.48 arcsec{-0.64 arcsec} ( 56-83 au). The size and position of the inner ring is in good agreement with previous polarimetric observations in the near-infrared and is consistent with dust trapping by a massive planet. No dust emission is detected inside the inner dust cavity (R ≲ 20 au) or within the dust gap ( 35-56 au) down to the noise level. In contrast, the channel maps of the J = 2-1 line of the three CO isotopologs reveal gas inside the dust cavity and dust gap. The gaseous disk is also much larger than the compact dust emission; it extends to 1.5 arcsec ( 180 au) in radius. This difference and the sharp drop of the continuum emission at large radii point to radial drift of large dust grains (>μm size). Using the thermo-chemical disk code dali, we modeled the continuum and the CO isotopolog emission to quantitatively measure the gas and dust surface densities. The resulting gas surface density is reduced by a factor of 30-40 inward of the dust gap. The gas and dust distribution indicate that two giant planets shape the disk structure through dynamical clearing (dust cavity and gap) and dust trapping (double-ring dust distribution).

  14. LOCATING THE TRAILING EDGE OF THE CIRCUMBINARY RING IN THE KH 15D SYSTEM

    SciTech Connect

    Capelo, Holly L.; Herbst, William; Leggett, S. K.; Hamilton, Catrina M.; Johnson, John A.

    2012-09-20

    Following two years of complete occultation of both stars in the binary T Tauri star KH 15D by its opaque circumbinary ring, KH 15D has abruptly brightened again during apastron phases, reaching I = 15 mag. Here, we show that the brightening is accompanied by a change in spectral class from K6/K7 (the spectral class of star A) to {approx}K1, and a bluing of the system in V - I by about 0.3 mag. A radial velocity measurement confirms that, at apastron, we are now seeing direct light from star B, which is more luminous and of earlier spectral class than star A. Evidently, the trailing edge of the occulting screen has just become tangent to one anse of star B's projected orbit. This confirms a prediction of the precession models, supports the view that the tilted ring is self-gravitating, and ushers in a new era of the system's evolution that should be accompanied by the same kind of dramatic phenomena observed from 1995 to 2009. It also promotes KH 15D from a single-lined to a double-lined eclipsing binary, greatly enhancing its value for testing pre-main-sequence models. The results of our study strengthen the case for truncation of the outer ring at around 4 AU by a sub-stellar object such as an extremely young giant planet. The system is currently at an optimal configuration for detecting the putative planet and we urge expedient follow-up observations.

  15. An injection system for PEP-based asymmetric storage ring collider for the copious production of B mesons

    SciTech Connect

    Barletta, W.A.

    1989-09-18

    The proposed asymmetric energy B-factory utilizing PEP will require high energy, low emittance sources of positrons and electrons suitable for filling the storage rings. Proposed characteristics of this collider operating at a luminosity of 10{sup 34} cm{sup -2}s{sup -1} have been studied by LBL (Apiary-III). The design consists of two rings, a large 9 GeV ring (PEP or a modification thereof) plus a smaller 3.1 GeV ring, each with a circulating current of 3 Amperes. Ideally the fill time should be much shorter than the luminosity life-time of the rings (set by the size of the low energy ring). As the luminosity lifetime of the collider is not expected to be very high, the PEP-based B-factory should have a powerful, dedicated injector. For the purpose of estimating the characteristics of the injection system the maximum time for a complete fill of the positron ring is taken to be {approx}100 seconds. The design of the injection system is discussed in this paper. 1 ref., 9 figs., 4 tabs.

  16. Universal cumulants of the current in diffusive systems on a ring.

    PubMed

    Appert-Rolland, C; Derrida, B; Lecomte, V; van Wijland, F

    2008-08-01

    We calculate exactly the first cumulants of the integrated current and of the activity (which is the total number of changes of configurations) of the symmetric simple exclusion process on a ring with periodic boundary conditions. Our results indicate that for large system sizes the large deviation functions of the current and of the activity take a universal scaling form, with the same scaling function for both quantities. This scaling function can be understood either by an analysis of Bethe ansatz equations or in terms of a theory based on fluctuating hydrodynamics or on the macroscopic fluctuation theory of Bertini, De Sole, Gabrielli, Jona-Lasinio, and Landim.

  17. Optical Properties of a Quantum Dot-Ring System Grown Using Droplet Epitaxy.

    PubMed

    Linares-García, Gabriel; Meza-Montes, Lilia; Stinaff, Eric; Alsolamy, S M; Ware, M E; Mazur, Y I; Wang, Z M; Lee, Jihoon; Salamo, G J

    2016-12-01

    Electronic and optical properties of InAs/GaAs nanostructures grown by the droplet epitaxy method are studied. Carrier states were determined by k · p theory including effects of strain and In gradient concentration for a model geometry. Wavefunctions are highly localized in the dots. Coulomb and exchange interactions are studied and we found the system is in the strong confinement regime. Microphotoluminescence spectra and lifetimes were calculated and compared with measurements performed on a set of quantum rings in a single sample. Some features of spectra are in good agreement.

  18. Novel, Broad Spectrum Anticancer Agents Containing the Tricyclic 5:7:5-Fused Diimidazodiazepine Ring System

    PubMed Central

    2010-01-01

    Synthesis of a series of novel, broad spectrum anticancer agents containing the tricyclic 5:7:5-fused diimidazo[4,5-d:4′,5′-f][1,3]diazepine ring system is reported. Compounds 1, 2, 8, 11, and 12 in the series show promising in vitro antitumor activity with low micromolar IC50 values against prostate, lung, breast, and ovarian cancer cell lines. Some notions about structure−activity relationships and a possible mechanism of biological activity are presented. Also presented are preliminary in vivo toxicity studies of 1 using SCID mice. PMID:21572541

  19. The amplitude and phase control of the ALS Storage Ring RF System

    SciTech Connect

    Lo, C.C.; Taylor, B.; Baptiste, K.

    1995-03-01

    A 500MHz, 300KW Klystron power amplifier provides RF power to the ALS Storage Ring. In order to accommodate the amplitude and phase changes during beam stacking and decay, which demand continuously varying power levels from the Klystron, four loops are used to keep the system operating properly, with two of those loops dedicated to keeping the two cavity tuners on tune. Description of the control loops and their performance data will be given. Using the modulation anode of the Klystron in the amplitude loop will be discussed.

  20. Universal cumulants of the current in diffusive systems on a ring

    NASA Astrophysics Data System (ADS)

    Appert-Rolland, C.; Derrida, B.; Lecomte, V.; van Wijland, F.

    2008-08-01

    We calculate exactly the first cumulants of the integrated current and of the activity (which is the total number of changes of configurations) of the symmetric simple exclusion process on a ring with periodic boundary conditions. Our results indicate that for large system sizes the large deviation functions of the current and of the activity take a universal scaling form, with the same scaling function for both quantities. This scaling function can be understood either by an analysis of Bethe ansatz equations or in terms of a theory based on fluctuating hydrodynamics or on the macroscopic fluctuation theory of Bertini, De Sole, Gabrielli, Jona-Lasinio, and Landim.

  1. Efficient Routing of Star-Ring Hybrid Topology with Optical Add and Drop Multiplexer in DWDM System

    NASA Astrophysics Data System (ADS)

    Bala, Anju; Dewra, Sanjeev

    2016-12-01

    This paper investigates the performance of star-ring hybrid topology networks with optical add and drop multiplexer (OADM) in dense wavelength division multiplexing (DWDM) system with 0.8 nm channel spacing at different bit rates (5, 10 and 15 Gbps) in terms of bit error rate (BER), quality factor and optical signal-to-noise ratio (OSNR). OADM has the capability to add and drop the new channels and provides the wavelength routing between star and ring topologies. It is observed that the hybrid topology supports 128 users on upper and lower ends with 150 km distance between the nodes of ring network without dispersion compensating fiber.

  2. Development of a bilayer ring system for achieving high strain in commercial rheometers.

    PubMed

    Christensen, Michael B; Wolchok, Jeffrey C; Klemuk, Sarah A; Titze, Ingo R

    2015-09-18

    Mechanical stimulation of cell cultures has been shown be an effective means of enhancing ECM production. ECM produced from vocal fold fibroblast cultures has the potential for therapeutic use for vocal fold repair. However, current bioreactor designs generally fail to produce physiological relevant frequency and strain values. Here we present an approach for using commercial oscillatory rheometers and an elastic ring bilayer system to produce physiologically relevant strain values at frequencies in the range of 20-100 Hz. We demonstrate the ability to target specific strain and frequency values by manipulating system parameters, and also show that it is possible to maintain high oscillatory strains for extended periods of time. Such a system could be used to mechanically stimulate cell cultures contained within gel carrier systems and has the potential to be extended to other applications requiring high strains at low frequencies.

  3. Cavity Ring-Down System for Density Measurement of Negative Hydrogen Ion on Negative Ion Source

    SciTech Connect

    Nakano, Haruhisa; Tsumori, Katsuyoshi; Nagaoka, Kenichi; Shibuya, Masayuki; Kisaki, Masashi; Ikeda, Katsunori; Osakabe, Masaki; Kaneko, Osamu; Asano, Eiji; Kondo, Tomoki; Sato, Mamoru; Komada, Seiji; Sekiguchi, Haruo; Takeiri, Yasuhiko; Fantz, Ursel

    2011-09-26

    A Cavity Ring-Down (CRD) system was applied to measure the density of negative hydrogen ion (H{sup -}) in vicinity of extraction surface in the H{sup -} source for the development of neutral beam injector on Large Helical Device (LHD). The density measurement with sampling time of 50 ms was carried out. The measured density with the CRD system is relatively good agreement with the density evaluated from extracted beam-current with applying a similar relation of positive ion sources. In cesium seeded into ion-source plasma, the linearity between an arc power of the discharge and the measured density with the CRD system was observed. Additionally, the measured density was proportional to the extracted beam current. These characteristics indicate the CRD system worked well for H{sup -} density measurement in the region of H{sup -} and extraction.

  4. Introduction to the magnet and vacuum systems of an electron storage ring

    SciTech Connect

    Weng, W.T.

    1982-08-15

    An accelerator or storage ring complex is a concerted interplay of various functional systems. For the convenience of discussion we can divide it into the following systems: injector, magnet, RF, vacuum, instrumentation and control. In addition, the conventional construction of the building and radiation safety consideration are also needed and finally the beam lines, detector, data acquisition and analysis set-ups for research programs. Dr. L. Teng has given a comprehensive review of the whole complex and the operation of such a facility. I concentrate on the description of magnet and vacuum systems. Only the general function of each system and the basic design concepts will be introduced, no detailed engineering practice will be given which will be best done after a machine design is produced. For further understanding and references a table of bibliography is provided at the end of the paper.

  5. Development of a computer control system for the RCNP ring cyclotron

    NASA Astrophysics Data System (ADS)

    Ogata, H.; Yamazaki, T.; Ando, A.; Hosono, K.; Itahashi, T.; Katayama, I.; Kibayashi, M.; Kinjo, S.; Kondo, M.; Miura, I.; Nagayama, K.; Noro, T.; Saito, T.; Shimizu, A.; Uraki, M.; Maruyama, M.; Aoki, K.; Yamada, S.; Kodaira, K.

    1990-08-01

    A hierarchically distributed computer control system for the RCNP ring cyclotron is being developed. The control system consists of a central computer and four subcomputers which are linked together by an Ethernet, universal device controllers which control component devices, man-machine interfaces including an operator console and interlock systems. The universal device controller is a standard single-board computer with an 8344 microcontroller and parallel interfaces, and is usually integrated into a component device and connected to a subcomputer by means of an optical-fiber cable to achieve high-speed data transfer. Control sequences for subsystems are easily produced and improved by using an interpreter language named OPELA (OPEration Language for Accelerators). The control system will be installed in March 1990.

  6. Molecular structure, interatomic interactions and vibrational analysis of 1,4-diazabicyclo[3.2.1]octane parent ring system

    NASA Astrophysics Data System (ADS)

    Britvin, Sergey N.; Rumyantsev, Andrey M.; Zobnina, Anastasia E.; Padkina, Marina V.

    2017-02-01

    Molecular structure of 1,4-diazabicyclo[3.2.1]octane, a parent ring of TAN1251 family of alkaloids, is herein characterized for the first time in comparison with the structure of nortropane (8-azabicyclo[3.2.1]octane), the parent framework of tropane ring system. The methods of study involve X-ray structural analysis, DFT geometry optimizations with infrared frequency calculations followed by natural bond orbital (NBO) analysis, and vibrational analysis of infrared spectrum.

  7. The Ring of Fire - an internal illimination system for detector sensitivity and filter bandpass characterization

    SciTech Connect

    Scarpine, Victor E.; Kent, Stephen M.; Deustua, Susana E.; Sholl, Michael J.; Mufson, Stuart L.; Ott, Melanie N.; Wiesner, Matthew P.; Baptitst, Brian J.; /Indiana U.

    2010-07-01

    We describe a prototype of an illumination system, the Ring of Fire (ROF), which is used as part of an internal calibration system for large focal plane detector arrays in TMA (Three Mirror Anastigmat) telescope designs. Such designs have been proposed for the SNAP (SuperNova Acceleration Probe) version of a Joint Dark Energy Mission (JDEM). The ROF system illuminates the focal plane with a light beam the closely matches that of the telescope and is used for creating high spatial frequency flat fields and monitoring filter bandpasses for experiments that demand a highly accurate characterization of the detectors. We present measurements of a mockup of this prototype ROF design including studies in variations in illumination across a large focal plane.

  8. Generation of optical frequency combs in a fiber-ring/microresonator laser system.

    PubMed

    Guo, Changlei; Che, Kaijun; Xu, Huiying; Zhang, Pan; Tang, Deyu; Ren, Changyan; Luo, Zhengqian; Cai, Zhiping

    2016-06-01

    We propose and experimentally demonstrate a simple scheme for generating optical frequency combs (OFCs) in a fiber-ring/microresonator laser system. The ultrahigh Q whispering gallery mode microresonator is employed both as a mode reflection mirror to generate erbium lasing and as a Kerr-nonlinearity initiator that introduces optical parametric oscillation signals to form OFCs. By controlling the coupling position between the fiber taper and microresonator, optimizing the fiber polarization, as well as the pump power from a 974 nm laser diode (LD), versatile OFCs can be tuned out from single-wavelength states. The OFCs have single, multiple, or combined free spectral ranges. In addition, a Raman-gain-assisted OFC is also observed with a bandwidth of ∼230  nm. This LD-pumped and multifunctional laser system could find applications in precision spectroscopy, biochemical sensing, and optical fiber communication systems.

  9. The trigger system for the external target experiment in the HIRFL cooling storage ring

    NASA Astrophysics Data System (ADS)

    Li, Min; Zhao, Lei; Liu, Jin-Xin; Lu, Yi-Ming; Liu, Shu-Bin; An, Qi

    2016-08-01

    A trigger system was designed for the external target experiment in the Cooling Storage Ring (CSR) of the Heavy Ion Research Facility in Lanzhou (HIRFL). Considering that different detectors are scattered over a large area, the trigger system is designed based on a master-slave structure and fiber-based serial data transmission technique. The trigger logic is organized in hierarchies, and flexible reconfiguration of the trigger function is achieved based on command register access or overall field-programmable gate array (FPGA) logic on-line reconfiguration controlled by remote computers. We also conducted tests to confirm the function of the trigger electronics, and the results indicate that this trigger system works well. Supported by the National Natural Science Foundation of China (11079003), the Knowledge Innovation Program of the Chinese Academy of Sciences (KJCX2-YW-N27), and the CAS Center for Excellence in Particle Physics (CCEPP).

  10. Hubble Observations of the Ongoing Evolution of Neptune's Ring-Moon System

    NASA Astrophysics Data System (ADS)

    Showalter, Mark Robert; de Pater, Imke; Lissauer, Jack J.; French, Robert S.

    2016-10-01

    We report on a new analysis of Hubble Space Telescope (HST) images of the Neptune system spanning 2004 to 2016. This expands upon an initial analysis we presented in 2013 (Showalter et al., DPS Meeting #45, abstract 206.01), based on HST images from 2004-2009. At that time we reported (1) the discovery of Neptune's fourteenth moon, S/2004 N 1, which orbits between Proteus and Larissa; (2) the recovery of Naiad, Neptune's innermost moon, although at an orbital longitude 90 degrees away from its prediction; and (3) the disappearance of the leading arcs in the Adams Ring, along with a marked decrease in the brightness of the trailing two arcs. Recent HST images extend the time baseline of the system by seven additional years, allowing us to expand upon prior results. We will report on our progress in refining the orbit, size and shape of S/2004 N 1, on understanding the orbital dynamics of Naiad, and on determining the ongoing evolution of the arcs and rings.

  11. Ring system-based chemical graph generation for de novo molecular design

    NASA Astrophysics Data System (ADS)

    Miyao, Tomoyuki; Kaneko, Hiromasa; Funatsu, Kimito

    2016-05-01

    Generating chemical graphs in silico by combining building blocks is important and fundamental in virtual combinatorial chemistry. A premise in this area is that generated structures should be irredundant as well as exhaustive. In this study, we develop structure generation algorithms regarding combining ring systems as well as atom fragments. The proposed algorithms consist of three parts. First, chemical structures are generated through a canonical construction path. During structure generation, ring systems can be treated as reduced graphs having fewer vertices than those in the original ones. Second, diversified structures are generated by a simple rule-based generation algorithm. Third, the number of structures to be generated can be estimated with adequate accuracy without actual exhaustive generation. The proposed algorithms were implemented in structure generator Molgilla. As a practical application, Molgilla generated chemical structures mimicking rosiglitazone in terms of a two dimensional pharmacophore pattern. The strength of the algorithms lies in simplicity and flexibility. Therefore, they may be applied to various computer programs regarding structure generation by combining building blocks.

  12. A new data acquisition system for Schottky signals in atomic physics experiments at GSI's and FAIR's storage rings

    NASA Astrophysics Data System (ADS)

    Trageser, C.; Brandau, C.; Kozhuharov, C.; Litvinov, Yu A.; Müller, A.; Nolden, F.; Sanjari, S.; Stöhlker, T.

    2015-11-01

    A new continuous and broadband data acquisition system for measurements of Schottky-signals of ions revolving in a storage ring has been implemented. This set-up is capable of recording the radio frequency (RF) signal of the ions that circulate in the storage ring with a sustained acquisition rate of more than 3.5× {10}7 IQ-samples per second. This allows several harmonics of the full momentum acceptance of a storage ring to be measured at the same time. The RF signal analyzer modules are complemented by further electronic modules such as counters, precision clocks and synchronization modules that facilitate a seamless integration with main experimental data acquisitions for atomic and nuclear physics. In this contribution, the setup and first results from a test run at the experimental storage ring at GSI, Darmstadt, Germany, are presented.

  13. Optical Analog to Electromagnetically Induced Transparency in Cascaded Ring-Resonator Systems

    PubMed Central

    Wang, Yonghua; Zheng, Hua; Xue, Chenyang; Zhang, Wendong

    2016-01-01

    The analogue of electromagnetically induced transparency in optical methods has shown great potential in slow light and sensing applications. Here, we experimentally demonstrated a coupled resonator induced transparency system with three cascaded ring coupled resonators in a silicon chip. The structure was modeled by using the transfer matrix method. Influences of various parameters including coupling ratio of couplers, waveguide loss and additional loss of couplers on transmission characteristic and group index have been investigated theoretically and numerically in detail. The transmission character of the system was measured by the vertical grating coupling method. The enhanced quality factor reached 1.22 × 105. In addition, we further test the temperature performance of the device. The results provide a new method for the manipulation of light in highly integrated optical circuits and sensing applications. PMID:27463720

  14. Negative ion fragmentations of deprotonated heterocycles. The isothiazole, thiazole, isoxazole, and oxazole ring systems

    NASA Astrophysics Data System (ADS)

    Adams, Gregory W.; Bowie, John H.; Hayes, Roger N.

    1992-05-01

    The major collision-induced dissociations of deprotonated isothiazole occur from the 5-anion, while deprotonated thiazole fragments almost equally through the 2- and 5-anions. Both 5-anions fragment by a simple retro cleavage yielding HC2S- and HCN. The 5-anion of isothiazole and the 2-anion of thiazole also rearrange to the common intermediate -SCH=CHCN which decomposes by losses of H2, HCN and H2S. There is no evidence for direct interconversion of isothiazole and thiazole anions. The spectra of deprotonated methylisothiazoles are complex, but the major fragmentations are of ring deprotonated ions and are generally analogous to the parent systems. The fragmentation behaviour of deprotonated isoxazole and oxazole is analogous to that of the isothiazole and thiazole systems.

  15. Vacuum system development status for the APS (Advanced Photon Source) storage ring

    SciTech Connect

    Wherle, R.; Nielson, R.; Kim, S.

    1989-01-01

    The status of the design and fabrication of a prototype sector of the storage ring vacuum system for the Advanced Photon Source is described. The 26.5-m-long prototype sector will be assembled within a full-scale magnet and tunnel mockup to study interspacial component relationships for maintenance, as well as the vacuum system operational performance. Each completed vacuum section is mounted as an integral part of the modular structure that contains the magnets and magnet power supplies on a common base. Unique automatic machine welding designs and techniques are employed in the fabrication of the aluminium vacuum chambers from extrusions. Special chamber bending procedures and measurements checks are used to maintain the required flatness of the insider chamber light gap surfaces. Photo-electron yields due to low-energy photons in the narrow channel gap of the vacuum chamber and their potential effects on the overall outgassing rate are found to be negligible. 9 refs., 5 figs.

  16. Vacuum system of the high energy ring of an asymmetric B-factory based on PEP

    SciTech Connect

    Barletta, W.A.; Calderon, M.O.; Wong, R. ); Jenkins, T.M. )

    1991-05-07

    The multi-ampere currents required for high luminosity operation of an asymmetric B factory leads to extremely stressing requirements on a vacuum system suitable for maintaining long beam-gas lifetimes and acceptable background levels in the detector. We present the design for a Cu alloy vacuum chamber and its associated pumping system for the 9 GeV electron storage ring of the proposed B factory based on PEP. The excellent thermal and photo-desorption properties of Cu allows handling the high proton flux in a conventional, single chamber design with distributed ion pumps. The x-ray opacity of the Cu is sufficiently high that no additional lead shielding is necessary to protect the dipoles from the intense synchrotron radiation generated by the beam. The design allows chamber commissioning in <500 hr of operation. 5 refs., 3 figs., 2 tabs.

  17. Intensity-demodulated fiber-ring laser sensor system for acoustic emission detection.

    PubMed

    Han, Ming; Liu, Tongqing; Hu, Lingling; Zhang, Qi

    2013-12-02

    We theoretically and experimentally demonstrate a fiber-optic ultrasonic sensor system based on a fiber-ring laser whose cavity consisting of a regular fiber Bragg grating (FBG) and a tunable optical band-pass filter (TOBPF). The FBG is the sensing element and the TOBPF is used to set the lasing wavelength at a point on the spectral slope of the FBG. The ultrasonic signal is detected by the variations of the laser output intensity in response to the cold-cavity loss modulations from the ultrasonically-induced FBG spectral shift. The system demonstrated here has a simple structure and low cost, making it attractive for acoustic emission detection in structure health monitoring.

  18. Reflective variable optical attenuators and fibre ring lasers for wavelength-division multiplexing systems

    NASA Astrophysics Data System (ADS)

    Liu, He Liang

    Wavelength division multiplexing (WDM) optical fibre system is an important enabling technology to fulfill the demands for bandwidth in the modern information age. The main objective of this project is to study novel devices with the potential to enhance the performance of WDM systems. In particular, a novel reflective variable optical attenuator (RVOA) used for dynamic gain equalization (DGE) and fibre lasers based on an entirely new type of erbium-doped fibres with ultrawide tuning range were investigated theoretically and experimentally. We proposed a new type of RVOA device which could be potentially integrated with arrayed waveguide grating (AWG) to reduce the cost of DGE substantially. Initially, fibre-based RVOAs, fabricated with optical fibre components such as fibre coupler and Faraday rotator mirror, were investigated theoretically and experimentally. Larger attenuation range up to 22 dB was realized for fibre coupler-based ROVA with a Faraday rotator mirror and its polarization-dependent loss is about 0.5 dB. Then polymeric waveguide-based RVOAs were investigated theoretically and experimentally. Using an epoxy Novolak resin as core material and an UV-cured resin (Norland's NOA61) as cladding material, a polymeric waveguide RVOA was successfully fabricated. The dynamic 15 dB attenuation range was achieved and the PDL was less than 0.2 dB. The measured insertion loss of the polymeric waveguide RVOA was too large (about 18 dB) and was mainly induced by coupling loss, material loss and poor alignment. In the second part of the study, fibre ring lasers with continuous wavelength tuning over wide wavelength range and fibre ring lasers with discrete wavelength tuning were investigated. Tunable lasers are important devices in WDM systems because they could be employed as reserved sources and therefore avoiding the need to stock large inventory of lasers to cover the ITU-wavelength grid. In this project, erbium ions doped bismuth oxide glass fibres instead of

  19. The Neptune System Revisited: New Results on Moons and Rings from the Hubble Space Telescope

    NASA Astrophysics Data System (ADS)

    Showalter, Mark R.; de Pater, I.; French, R. S.; Lissauer, J. J.

    2013-10-01

    We report on observations of Neptune's rings, arcs and inner moons as obtained by the Hubble Space Telescope during 2004-2009. These are the only Earth-based observations of the ring system obtained at visual wavelengths, permitting direct photometric comparison with the Voyager images. This allows us to determine quantitatively how the arcs have evolved from the time they were first imaged. Of the four arcs identified in 1989, the leading two have vanished, but the trailing two appear to have remained quite stable. New analysis of the images has also revealed a small moon, S/2004 N 1, orbiting between Proteus and Larissa. The body has a mean motion of 378.907 +/- 0.001 degrees per day, corresponding to semimajor axis 105,283 km. Its V magnitude is 26.5 +/- 0.3, suggesting a radius of ~ 10 km if its albedo is ~ 10%, comparable to that of the other inner moons. Tentative detections of Naiad, the smallest moon discovered by Voyager, will also be discussed.

  20. Electromagnetic Calculation of Combined Earthing System with Ring Earth Electrode and Vertical Rods for Wind Turbine

    NASA Astrophysics Data System (ADS)

    Fujii, Toshiaki; Yasuda, Yoh; Ueda, Toshiaki

    With the worldwide spread of wind turbine installations, various problems such as landscape issues, bird strikes and grid connections have arisen. Protection of wind turbines from lightning is cited as one of the main problems. Wind turbines are often struck by lightning because of their open-air locations, such as in mountainous areas, and their special configuration and very-high construction. Especially, low-voltage and control circuits can fail or suffer burnout while blades can incur serious damage if struck by lightning. Wind turbine failures caused by lightning strikes account for approximately 25% of all failures. The problem is regarded as a global one that needs immediate resolution. It is important to understand the impedance characteristics of wind turbine earthing systems from the viewpoint of lightning protection. A report from IEC TR61400-24 recommends a “ring earth electrode”. This was originally defined in IEC 61024 (currently revised and re-numbered as IEC 62305), where such an electrode is recommended to reduce touch and step voltages in households and buildings. IEC TR61400-24 also recommended additional electrodes of vertical or horizontal rods. However, these concepts have not been fully discussed from the viewpoint of its application to wind turbines. To confirm the effect of a combination of a ring earth electrode and additional vertical rods for protection of a wind turbine, this report uses the Finite Difference Time Domain (FDTD) method to present an electromagnetic transient analysis on such a wind turbine earthing system. The results show that an optimal combination can be arranged from viewpoints of lightning protection and construction cost. Thus, this report discusses how to establish a quantitative design methodology of the wind turbine earthing system to provide effective lightning protection.

  1. A wireless fatigue monitoring system utilizing a bio-inspired tree ring data tracking technique.

    PubMed

    Bai, Shi; Li, Xuan; Xie, Zhaohui; Zhou, Zhi; Ou, Jinping

    2014-03-05

    Fatigue, a hot scientific research topic for centuries, can trigger sudden failure of critical structures such as aircraft and railway systems, resulting in enormous casualties as well as economic losses. The fatigue life of certain structures is intrinsically random and few monitoring techniques are capable of tracking the full life-cycle fatigue damage. In this paper, a novel in-situ wireless real-time fatigue monitoring system using a bio-inspired tree ring data tracking technique is proposed. The general framework, methodology, and verification of this intelligent system are discussed in details. The rain-flow counting (RFC) method is adopted as the core algorithm which quantifies fatigue damages, and Digital Signal Processing (DSP) is introduced as the core module for data collection and analysis. Laboratory test results based on strain gauges and polyvinylidene fluoride (PVDF) sensors have shown that the developed intelligent system can provide a reliable quick feedback and early warning of fatigue failure. With the merits of low cost, high accuracy and great reliability, the developed wireless fatigue sensing system can be further applied to mechanical engineering, civil infrastructures, transportation systems, aerospace engineering, etc.

  2. A Wireless Fatigue Monitoring System Utilizing a Bio-Inspired Tree Ring Data Tracking Technique

    PubMed Central

    Bai, Shi; Li, Xuan; Xie, Zhaohui; Zhou, Zhi; Ou, Jinping

    2014-01-01

    Fatigue, a hot scientific research topic for centuries, can trigger sudden failure of critical structures such as aircraft and railway systems, resulting in enormous casualties as well as economic losses. The fatigue life of certain structures is intrinsically random and few monitoring techniques are capable of tracking the full life-cycle fatigue damage. In this paper, a novel in-situ wireless real-time fatigue monitoring system using a bio-inspired tree ring data tracking technique is proposed. The general framework, methodology, and verification of this intelligent system are discussed in details. The rain-flow counting (RFC) method is adopted as the core algorithm which quantifies fatigue damages, and Digital Signal Processing (DSP) is introduced as the core module for data collection and analysis. Laboratory test results based on strain gauges and polyvinylidene fluoride (PVDF) sensors have shown that the developed intelligent system can provide a reliable quick feedback and early warning of fatigue failure. With the merits of low cost, high accuracy and great reliability, the developed wireless fatigue sensing system can be further applied to mechanical engineering, civil infrastructures, transportation systems, aerospace engineering, etc. PMID:24603635

  3. Small-animal whole-body imaging using a photoacoustic full ring array system

    NASA Astrophysics Data System (ADS)

    Xia, Jun; Guo, Zijian; Aguirre, Andres; Zhu, Quing; Wang, Lihong V.

    2011-03-01

    In this report, we present a novel 3D photoacoustic computed tomography (PACT) system for small-animal whole-body imaging. The PACT system, based on a 512-element full-ring transducer array, received photoacoustic signals primarily from a 2-mm-thick slice. The light was generated by a pulse laser, and can either illuminate from the top or be reshaped to illuminate the sample from the side, using a conical lens and an optical condenser. The PACT system was capable of acquiring an in-plane image in 1.6 s; by scanning the sample in the elevational direction, a 3D tomographic image could be constructed. We tested the system by imaging a cylindrical phantom made of human hairs immersed in a scattering medium. The reconstructed image achieved an in-plane resolution of 0.1 mm and an elevational resolution of 1 mm. After deconvolution in the elevational direction, the 3D image was found to match well with the phantom. The system was also used to image a baby mouse in situ; the spinal cord and ribs can be seen easily in the reconstructed image. Our results demonstrate that the PACT system has the potential to be used for fast small-animal whole-body tomographic imaging.

  4. Performance of the front end electronics and data acquisition system for the SLD Cherenkov Ring Imaging Detector

    SciTech Connect

    Abe, K.; Hasegawa, K.; Suekane, F.; Yuta, H. . Dept. of Physics); Antilogus, P.; Aston, D.; Bienz, T.; Bird, F.; Dasu, S.; Dolinsky, S.; Dunwoodie, W.; Hallewell, G.; Hoeflich, J.; Kawahara, H.; Kwon, Y.; Leith, D.W.G.S.; Marshall, D.; Muller, D.; Nagamine, T.; Oxoby, G.; Pavel, T.J.; Ratcliff, B.; Rensing, P.; Schultz, D.; Shapiro, S.; Simopoulos, C.; Solodov, E.; Stiles, P.; Toge, N.; Va'vra, J

    1991-11-01

    The front end electronics and data acquisition system for the SLD barrel Cherenkov Ring Imaging Detector (CRID) are described. This electronics must provide a 1% charge division measurement with a maximum acceptable noise level of 2000 electrons (rms). Noise and system performance results are presented for the initial SLD engineering run data.

  5. Simulating the Librational Behaviour of Propeller Moons In The Saturnian Ring System

    NASA Astrophysics Data System (ADS)

    Seiler, Michael; Seiss, Martin; Hoffmann, Holger; Spahn, Frank

    2016-10-01

    The propeller structure Blériot orbiting in the outer A ring of the Saturnian ring system has been one of the tremendous discoveries of the spacecraft Cassini [Tiscareno et al., 2010, ApJL]. The reconstruction of the orbital evolution of Blériot from recurrent observations in the ISS images yielded a systematic offset motion from the expected Keplerian orbit. This offset motion can be well described by three sinusoidal harmonics with amplitudes and periods of 1845, 152, 58 km and 11.1, 3.7 and 2.2 years, respectively [Sremčević et al., 2014, EPSC]. Oscillatory deviations from the Keplerian orbit are a known phenomenon for the Saturnian moons, which can be explained by resonant interactions with other moons [Spitale et al., 2006, AJ] and which look similar to the observation of Blériot.In this work we present our results from N-Body simulations, where we integrated the orbital evolution of a test particle, orbiting at the radial position of the propeller Blériot and 15 other moons of Saturn. Our simulation yield, that gravitational interactions with the larger moons result in reasonable and observable frequencies, but the resulting amplitudes of the librations are by far too small to explain the observations. Further mechanisms are needed, to amplify the amplitudes of the forced librations -- as e.g. by moonlet-ring interactions. Inspired by the recent work of Pan and Chiang [2010, ApJL; 2012, AJ] we introduce an alternative, physically more reasonable model. In our model, the moonlet is allowed to be slightly displaced with respect to its created gaps, resulting in a repulsive force. As a result, the moonlet's longitude starts to oscillate. In the presence of the additional external forcing by the outer moons the libration amplitude gets amplified, if the forcing frequency is close to the eigenfrequency of the system. Applying our model to Blériot, we can indeed reproduce a libration period of 13 years with an amplitude of about 2000 km.

  6. Photonic crystal channel drop filter based on ring-shaped defects for DWDM systems

    NASA Astrophysics Data System (ADS)

    Dideban, Ali; Habibiyan, Hamidreza; Ghafoorifard, Hassan

    2017-03-01

    This paper presents a novel configuration of channel drop filters based on two-dimensional photonic crystal slabs in silicon-on-insulator platforms. The structure is composed of two photonic crystal line-defect waveguides as input and output ports, along with an L3 cavity with ring-shaped border holes. The effects of structural parameters and fabrication errors on resonance frequency and drop efficiency are investigated. Band structure and propagation of electromagnetic field through device are calculated by plane wave expansion and finite-difference time-domain methods. The results show that the quality factor and line-width of output signal are 5690 and 0.27 nm, respectively, indicating that the proposed filter can be properly used in dense wavelength division multiplexing systems with 0.8 nm channel spacing.

  7. Improved thermometry of low-temperature quantum systems by a ring-structure probe

    NASA Astrophysics Data System (ADS)

    Guo, Li-Sha; Xu, Bao-Ming; Zou, Jian; Shao, Bin

    2015-11-01

    The thermometry precision of a sample is a question of both fundamental and technological importance. In this paper, we consider a ring-structure system as our probe to estimate the temperature of a bath. Based on the Markovian master equation of the probe, we calculate the quantum Fisher information (QFI) of the probe at any time. We find that for the thermal equilibrium thermometry, the ferromagnetic structure can measure a lower temperature of the bath with a higher precision compared with the nonstructure probe, while for the dynamical thermometry, the antiferromagnetic structure can make the QFI of the probe in the dynamical process much larger than that in equilibrium with the bath, which is somewhat counterintuitive. Moreover, the best accuracy for the thermometry achieved in the antiferromagnetic structure case can be much higher than that in the nonstructure case. The physical mechanisms of the above phenomena are given in this paper.

  8. Synthesis of the ABCDEF and FGHI ring system of yessotoxin and adriatoxin

    PubMed Central

    Zhang, Yuan; Rainier, Jon D.

    2016-01-01

    Yessotoxin and adriatoxin are members of the polycyclic ether family of marine natural products. Outlined in this article is our synthetic approach to two subunits of these targets. Central to our strategy is a coupling sequence that employs an olefinic-ester cyclization reaction. As outlined, this sequence was used in two coupling sequences. First it was used to merge the A,B- and E,F-bicyclic precursors and in the process generate the C, D-rings. Second it was used to couple the F- and I-rings while building the eight-membered G-ring and subsequently the H-ring pyran. PMID:26956788

  9. Saturn's largest ring.

    PubMed

    Verbiscer, Anne J; Skrutskie, Michael F; Hamilton, Douglas P

    2009-10-22

    Most planetary rings in the Solar System lie within a few radii of their host body, because at these distances gravitational accelerations inhibit satellite formation. The best known exceptions are Jupiter's gossamer rings and Saturn's E ring, broad sheets of dust that extend outward until they fade from view at five to ten planetary radii. Source satellites continuously supply the dust, which is subsequently lost in collisions or by radial transport. Here we report that Saturn has an enormous ring associated with its outer moon Phoebe, extending from at least 128R(S) to 207R(S) (Saturn's radius R(S) is 60,330 km). The ring's vertical thickness of 40R(S) matches the range of vertical motion of Phoebe along its orbit. Dynamical considerations argue that these ring particles span the Saturnian system from the main rings to the edges of interplanetary space. The ring's normal optical depth of approximately 2 x 10(-8) is comparable to that of Jupiter's faintest gossamer ring, although its particle number density is several hundred times smaller. Repeated impacts on Phoebe, from both interplanetary and circumplanetary particle populations, probably keep the ring populated with material. Ring particles smaller than centimetres in size slowly migrate inward and many of them ultimately strike the dark leading face of Iapetus.

  10. New insights into the chemistry and antioxidant activity of coumarins.

    PubMed

    Torres, Fernando Cidade; Brucker, Natália; Andrade, Saulo Fernandes; Kawano, Daniel Fabio; Garcia, Solange Cristina; Poser, Gilsane Lino von; Eifler-Lima, Vera Lucia

    2014-01-01

    Coumarins are considered to be privileged structures due to their broad range of biological properties, including anticoagulant, anti-neurodegenerative, antioxidant, anticancer and antimicrobial activities. These interesting properties of coumarins can be ascribed to the chemical attributes of the 2H-chromen-2-one core; its aromatic ring can establish a series of hydrophobic, π-π, CH-π and cation-π interactions, and the two oxygen atoms in the lactone ring may hydrogen-bond to a series of amino acid residues in different classes of enzymes and receptors. Additionally, the double bond in the lactone helps to make the entire system planar, allows charge delocalization between the carbonyl group of the lactone and the aromatic ring and confers the characteristic fluorescence of this class of compounds, which can be explained by their preventing the trans-cis transformation of the double bond under ultraviolet (UV) irradiation. It is the possibility of radical delocalization in the 2H-chromen-2-one nucleus that makes most of the coumarins good antioxidants by acting as free radical scavengers, although some coumarins (mainly hydroxycoumarins) may also prevent the formation of free radicals by chelating metal ions. In this review, we provide a systematic analysis of the most important aspects surrounding the development of coumarins as antioxidants. Our analysis includes the synthesis of some complex antioxidant coumarins, strategies for structural modification to improve their antioxidant activities, qualitative/ quantitative structure-antioxidant relationships studies and the main in vitro assays used to evaluate their antioxidant properties.

  11. Novel DC ring topology and protection system - a comprehensive solution for mega city power grids

    NASA Astrophysics Data System (ADS)

    Haj-Maharsi, Mohamed Yassine

    2009-07-01

    The development of mega cities leads to increased load concentration and brings additional challenges to managing the electrical grid while keeping power available for critical loads. Techniques using FACTS devices are being applied to alleviate power management difficulties and to confine faults in their originating areas in order to limit the risk of cascading failures in the grid. The addition of many FACTS devices often results in control and protection coordination difficulties, power oscillations between connected networks, subsynchronous resonance problems, and torsional interactions with nearby generator units. The most effective solution is obtained when the individual AC subsystems representing sources and loads are decoupled so a fault in a given subsystem is not propagated to another subsystem. This solution can be achieved by the deployment of a DC system where power sources and loads are connected to the DC bus through voltage source converters. For a mega city, this would be conceived as a DC ring feeding multiple loads and connected to remote and local power sources. Unfortunately, the lack of fast DC circuit breakers has been one of the key issues affecting extensive applications of DC systems with common DC buses; a DC fault would discharge all the capacitors of the DC bus and cause delays in system recovery and possibly a wide system collapse. In this research, I provide a comprehensive solution to mega city power grid problems by proposing a DC system topology that enables grid expansions without affecting existing protection settings or changing existing AC breaker ratings. I also propose the means for protecting the DC system by designing a fast DC breaker and developing a control algorithm capable of isolating DC faults without blocking converter stations or depleting DC bus capacitors. My contribution is three folds: (1) I modeled and simulated Shanghai power grid and performed a study to identify short circuit and voltage stability problems

  12. Design, synthesis and anticancer screening of 3-(3-(substituted phenyl) acryloyl)-2H-chromen-2ones as selective anti-breast cancer agent.

    PubMed

    Mokale, Santosh N; Begum, Afreen; Sakle, Nikhil S; Shelke, Vishakha R; Bhavale, Swati A

    2017-03-09

    By utilizing concept of molecular hybridization, involving combination of various Pharmacophore, novel substituted coumarin-chalcone hybrids was synthesized and evaluated for anti-proliferative activity against estrogen receptor-positive MCF-7 and negative MDA-MB-435 breast cancer cell lines. In-vivo study was carried out by N-methyl nitrosourea (MNU) induced mammary carcinoma in virgin female Spraque Dawly (SD) rats. The compound 5b has highest potential than standard drug Adriamycin, comparable against Tamoxifen against ER-positive MCF-7 breast cancer cell lines. Docking study was performed to study the binding orientation and affinity of synthesized compounds on the ER-α enzyme.

  13. Rotating machinery dynamics simulation. I. Rigid systems with ball bearing nonlinearities and outer ring ovality under rotating unbalance excitation

    PubMed

    el-Saeidy

    2000-02-01

    The radial clearance in rolling bearing systems, required to compensate for dimensional changes associated with thermal expansion of the various parts during operation, may cause dimensional attrition and comprise bearing life, if unloaded operation occurs and balls skid [D. Childs and D. Moyer, ASME J. Eng. Gas Turb. Power 107, 152-159 (1985)]. Also, it can cause jumps in the response to unbalance excitation. These undesirable effects may be eliminated by introducing two or more loops into one of the bearing races so that at least two points of the ring circumference provide a positive zero clearance [D. Childs, Handbook of Rotordynamics, edited by F. Ehrich (McGraw-Hill, NY, 1992)]. The deviation of the outer ring with two loops, known as ovality, is one of the bearing distributed defects. Although this class of imperfections has received much work, none of the available studies has simulated the effect of the outer ring ovality on the dynamic behavior of rotating machinery under rotating unbalance with consideration of ball bearing nonlinearities, shaft elasticity, and speed of rotation. To fill this gap, the equations of motion of a rotor-ball bearing system are formulated using finite-elements (FE) discretization and Lagrange's equations. The analyses are specialized to a rigid-rotor system, by retaining the rigid body modes only in the FE solution. Samples of the results are presented in both time domain and frequency domain for a system with and without outer ring ovality. It is found that with ideal bearings (no ovality), the vibration spectrum is qualitatively and quantitatively the same in both the horizontal and vertical directions. When the ring ovality is introduced, however, the spectrum in both orthogonal planes is no longer similar. And magnitude of the bearing load has increased in the form of repeated random impacts, between balls and rings, in the horizontal direction (direction of maximum clearance) compared to a continuous contact along the

  14. MRI-compatible ultrasound heating system with ring-shaped phased arrays for breast tumor thermal therapy.

    PubMed

    Chen, Hung-Nien; Chen, Guan-Ming; Lin, Bo-Sian; Lien, Pi-Hsien; Chen, Yung-Yaw; Chen, Gin-Shin; Lin, Win-Li

    2013-01-01

    Therapeutic ultrasound transducers can carry out precise and efficient power deposition for tumor thermal therapy under the guidance of magnetic resonance imaging. For a better heating, organ-specific ultrasound transducers with precision location control system should be developed for tumors located at various organs. It is feasible to perform a better heating for breast tumor thermal therapy with a ring-shaped ultrasound phased-array transducer. In this study, we developed ring-shaped phased-array ultrasound transducers with 1.0 and 2.5 MHz and a precision location control system to drive the transducers to the desired location to sonicate the designated region. Both thermo-sensitive hydrogel phantom and ex vivo fresh pork were used to evaluate the heating performance of the transducers. The results showed that the ring-shaped phased array ultrasound transducers were very promising for breast tumor heating with the variation of heating patterns and without overheating the ribs.

  15. Initial test results of the Los Alamos proton-storage-ring bump-magnet system

    SciTech Connect

    Rose, C.R.; Barlow, D.B.; Redd, D.B.

    1997-09-01

    An upgrade program for increasing the stored beam current in the LANSCE Proton Storage is presently under way. Part of the upgrade effort has been to design, specify, and add four bump-magnet/modulator systems to the ring. This paper describes the initial test results of the first bump-magnet/modulator system. The paper begins with an overview of the pulsed-power system including important specifications of the modulator, magnet, cabling, and control system. In the main portion of the paper, waveforms and test data are included showing the accuracy, repeatability, and stability of the magnet-current pulses. These magnet pulses are programmable both in rise and fall time as well as in amplitude. The amplitude can be set between 50 and 300 A, the rise-time is fixed at 1 ms, and the linear fall-time can be varied between 500 {mu}s and 1500 {mu}s. Other issues such as loading effects and power dissipation in the magnet-bore beamtube are examined and reported.

  16. Intravaginal rings as delivery systems for microbicides and multipurpose prevention technologies

    PubMed Central

    Thurman, Andrea Ries; Clark, Meredith R; Hurlburt, Jennifer A; Doncel, Gustavo F

    2013-01-01

    There is a renewed interest in delivering pharmaceutical products via intravaginal rings (IVRs). IVRs are flexible torus-shaped drug delivery systems that can be easily inserted and removed by the woman and that provide both sustained and controlled drug release, lasting for several weeks to several months. In terms of women’s health care products, it has been established that IVRs effectively deliver contraceptive steroids and steroids for the treatment of postmenopausal vaginal atrophy. A novel application for IVRs is the delivery of antiretroviral drugs for the prevention of human immunodeficiency virus (HIV) genital infection. Microbicides are antiviral drugs delivered topically for HIV prevention. Recent reviews of microbicide IVRs have focused on technologies in development and optimizing ring design. IVRs have several advantages, including the ability to deliver sustained drug doses for long periods of time while bypassing first pass metabolism in the gut. IVRs are discreet, woman-controlled, and do not require a trained provider for placement or fitting. Previous data support that women and their male sexual partners find IVRs highly acceptable. Multipurpose prevention technology (MPT) products provide protection against unintended/mistimed pregnancy and reproductive tract infections, including HIV. Several MPT IVRs are currently in development. Early clinical testing of new microbicide and MPT IVRs will require a focus on safety, pharmacokinetics and pharmacodynamics. Specifically, IVRs will have to deliver tissue concentrations of drugs that are pharmacodynamically active, do not cause mucosal alterations or inflammation, and do not change the resident microbiota. The emergence of resistance to antiretrovirals will need to be investigated. IVRs should not disrupt intercourse or have high rates of expulsion. Herein, we reviewed the microbicide and MPT IVRs currently in development, with a focus on the clinical aspects of IVR assessment and the challenges

  17. Dust and Planetary Rings

    NASA Astrophysics Data System (ADS)

    Siddiqui, Muddassir

    ABSTRACT Space is not empty it has comic radiations (CMBR), dust etc. Cosmic dust is that type of dust which is composed of particles in space which vary from few molecules to 0.1micro metres in size. This type of dust is made up of heavier atoms born in the heart of stars and supernova. Mainly it contains dust grains and when these dust grains starts compacting then it turns to dense clouds, planetary ring dust and circumstellar dust. Dust grains are mainly silicate particles. Dust plays a major role in our solar system, for example in zodiacal light, Saturn's B ring spokes, planetary rings at Jovian planets and comets. Observations and measurements of cosmic dust in different regions of universe provide an important insight into the Universe's recycling processes. Astronomers consider dust in its most recycled state. Cosmic dust have radiative properties by which they can be detected. Cosmic dusts are classified as intergalactic dusts, interstellar dusts and planetary rings. A planetary ring is a ring of cosmic dust and other small particles orbiting around a planet in flat disc shape. All of the Jovian planets in our solar system have rings. But the most notable one is the Saturn's ring which is the brightest one. In March 2008 a report suggested that the Saturn's moon Rhea may have its own tenuous ring system. The ring swirling around Saturn consists of chunks of ice and dust. Most rings were thought to be unstable and to dissipate over course of tens or hundreds of millions of years but it now appears that Saturn's rings might be older than that. The dust particles in the ring collide with each other and are subjected to forces other than gravity of its own planet. Such collisions and extra forces tend to spread out the rings. Pluto is not known to have any ring system but some Astronomers believe that New Horizons probe might find a ring system when it visits in 2015.It is also predicted that Phobos, a moon of Mars will break up and form into a planetary ring

  18. Beam position controlling method for 3D optical system and its application in non-planar ring resonators.

    PubMed

    Yuan, Jie; Chen, Meixiong; Long, Xingwu; Tan, Yanyang; Kang, Zhenglong; Li, Yingying

    2012-08-13

    A novel theoretical beam position controlling method for 3D optical system has been proposed in this paper. Non-planar ring resonator, which is a typical 3D optical system, has been chosen as an example to show its application. To the best of our knowledge, the generalized ray matrices, augmented 5 × 5 ray matrices for paraxial dielectric interface transmission and paraxial optical-wedge transmission, and their detailed deducing process have been proposed in this paper for the first time. By utilizing the novel coordinate system for Gaussian beam reflection and the generalized ray matrix of paraxial optical-wedge transmission, the rules and some novel results of the optical-axis perturbations of non-planar ring resonators have been obtained. Wedge angle-induced mismatching errors of non-planar ring resonators have been found out and two experimental beam position controlling methods to effectively eliminate the wedge angle-induced mismatching errors have been proposed. All those results have been confirmed by related alignment experiments and the experimental results have been described with diagrammatic representation. These findings are important to the beam control, cavity design, and cavity alignment of high precision non-planar ring laser gyroscopes. Those generalized ray matrices and their deducing methods are valuable for ray analysis of various kinds of paraxial optical-elements and resonators. This novel theoretical beam position controlling method for 3D optical system is valuable for the controlling of various kinds of 3D optical systems.

  19. Pi overlapping ring systems contained in a homogeneous assay: a novel homogeneous assay for antigens

    NASA Astrophysics Data System (ADS)

    Kidwell, David A.

    1993-05-01

    A novel immunoassay, Pi overlapping ring systems contained in a homogeneous assay (PORSCHA), is described. This assay relies upon the change in fluorescent spectral properties that pyrene and its derivatives show with varying concentration. Because antibodies and other biomolecules can bind two molecules simultaneously, they can change the local concentration of the molecules that they bind. This concentration change may be detected spectrally as a change in the fluorescence emission wavelength of an appropriately labeled biomolecule. Several tests of PORSCHA have been performed which demonstrate this principle. For example: with streptavidin as the binding biomolecule and a biotin labeled pyrene derivative, the production of the excimer emitting at 470 nm is observed. Without the streptavidin present, only the monomer emitting at 378 and 390 nm is observed. The ratio of monomer to excimer provides the concentration of unlabeled biotin in the sample. Approximately 1 ng/mL of biotin may be detected with this system using a 50 (mu) l sample (2 X 10-16 moles biotin). The principles behind PORSCHA, the results with the streptavidin/biotin system are discussed and extensions of the PORSCHA concept to antibodies as the binding partner and DNA in homogeneous assays are suggested.

  20. Flight test results of the strapdown ring laser gyro tetrad inertial navigation system

    NASA Technical Reports Server (NTRS)

    Carestia, R. A.; Hruby, R. J.; Bjorkman, W. S.

    1983-01-01

    A helicopter flight test program undertaken to evaluate the performance of Tetrad (a strap down, laser gyro, inertial navigation system) is described. The results of 34 flights show a mean final navigational velocity error of 5.06 knots, with a standard deviation of 3.84 knots; a corresponding mean final position error of 2.66 n. mi., with a standard deviation of 1.48 n. mi.; and a modeled mean position error growth rate for the 34 tests of 1.96 knots, with a standard deviation of 1.09 knots. No laser gyro or accelerometer failures were detected during the flight tests. Off line parity residual studies used simulated failures with the prerecorded flight test and laboratory test data. The airborne Tetrad system's failure--detection logic, exercised during the tests, successfully demonstrated the detection of simulated ""hard'' failures and the system's ability to continue successfully to navigate by removing the simulated faulted sensor from the computations. Tetrad's four ring laser gyros provided reliable and accurate angular rate sensing during the 4 yr of the test program, and no sensor failures were detected during the evaluation of free inertial navigation performance.

  1. Jupiter's Main Ring/Ring Halo

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A mosaic of four images taken through the clear filter (610 nanometers) of the solid state imaging (CCD) system aboard NASA's Galileo spacecraft on November 8, 1996, at a resolution of approximately 46 kilometers (28.5 miles) per picture element (pixel) along Jupiter's rings. Because the spacecraft was only about 0.5 degrees above the ring plane, the image is highly foreshortened in the vertical direction. The images were obtained when Galileo was in Jupiter's shadow, peering back toward the Sun; the ring was approximately 2.3 million kilometers (1.4 million miles) away. The arc on the far right of the image is produced when sunlight is scattered by small particles comprising Jupiter's upper atmospheric haze. The ring also efficiently scatters light, indicating that much of its brightness is due to particles that are microns or less in diameter. Such small particles are believed to have human-scale lifetimes, i.e., very brief compared to the solar system's age.

    Jupiter's ring system is composed of three parts - - a flat main ring, a lenticular halo interior to the main ring, and the gossamer ring, outside the main ring. The near and far arms of Jupiter's main ring extend horizontally across the mosaic, joining together at the ring's ansa, on the figure's far left side. The near arm of the ring appears to be abruptly truncated close to the planet, at the point where it passes into Jupiter's shadow. Some radial structure is barely visible across the ring's ansa (top image). A faint mist of particles can be seen above and below the main rings. This vertically extended 'halo' is unusual in planetary rings, and is probably caused by electromagnetic forces pushing the smallest grains out of the ring plane. Because of shadowing, the halo is not visible close to Jupiter in the lower right part of the mosaic. To accentuate faint features in the bottom image of the ring halo, different brightnesses are shown through color. Brightest features are white or yellow and the

  2. Synthesis and antiproliferative activity of the ring system [1,2]oxazolo[4,5-g]indole.

    PubMed

    Barraja, Paola; Caracausi, Libero; Diana, Patrizia; Spanò, Virginia; Montalbano, Alessandra; Carbone, Anna; Parrino, Barbara; Cirrincione, Girolamo

    2012-11-01

    Brand new ring: A series of 27 derivatives of the new ring system [1,2]oxazolo[4,5-g]indole were conveniently prepared and tested at the NCI for antiproliferative studies. Several of them showed good inhibitory activity toward all tested cell lines, reaching GI50 values generally at the micromolar and sub-micromolar levels and in some cases at nanomolar concentrations. The mean GI50 values, calculated on the full panel, were in the range 0.25-7.08 μM.

  3. Limits on Pluto's ring system from the June 12 2006 stellar occultation and implications for the New Horizons impact hazard

    NASA Astrophysics Data System (ADS)

    Throop, Henry B.; French, Richard G.; Shoemaker, Kevin; Olkin, Cathy B.; Ruhland, Trina R.; Young, Leslie A.

    2015-01-01

    The Pluto system passed in front of a 15th magnitude star on 12 June 2006. We observed this occultation from the 3.9 m Anglo-Australian Telescope (AAT), and took photometric observations every 100 ms for 3 h. Our three-hour baseline of data provides among the longest and highest-quality occultation dataset of the Pluto system ever taken. Results on Pluto's atmospheric structure from these data have been previously reported (Young, E.F. [2008]. Astron. J. 136, 1757-1769). Here we report on limits for rings, ring arcs, and small satellites within the system. We find a 3 σ upper limit on the normal optical depth of τ < 0.07 for narrow rings of width 2.4 km, and τ < 5 ×10-3 for rings of width 1500 km. We also detect no discrete objects of radius 220 m or larger along the occultation path. Motivated by the upcoming flyby of New Horizons through the Pluto system, we estimate the dust impact hazard to the spacecraft based on our optical depth limits and those derived from imaging with the Hubble Space Telescope.

  4. Circumbinary ring, circumstellar disks, and accretion in the binary system UY Aurigae

    SciTech Connect

    Tang, Ya-Wen; Ho, Paul T. P.; Dutrey, Anne; Guilloteau, Stéphane; Di Folco, Emmanuel; Piétu, Vincent; Gueth, Fréderic; Beck, Tracy; Boehler, Yann; Bary, Jeff; Simon, Michal

    2014-09-20

    Recent exo-planetary surveys reveal that planets can orbit and survive around binary stars. This suggests that some fraction of young binary systems which possess massive circumbinary (CB) disks may be in the midst of planet formation. However, there are very few CB disks detected. We revisit one of the known CB disks, the UY Aurigae system, and probe {sup 13}CO 2-1, C{sup 18}O 2-1, SO 5(6)-4(5) and {sup 12}CO 3-2 line emission and the thermal dust continuum. Our new results confirm the existence of the CB disk. In addition, the circumstellar (CS) disks are clearly resolved in dust continuum at 1.4 mm. The spectral indices between the wavelengths of 0.85 mm and 6 cm are found to be surprisingly low, being 1.6 for both CS disks. The deprojected separation of the binary is 1.''26 based on our 1.4 mm continuum data. This is 0.''07 (10 AU) larger than in earlier studies. Combining the fact of the variation of UY Aur B in R band, we propose that the CS disk of an undetected companion UY Aur Bb obscures UY Aur Ba. A very complex kinematical pattern inside the CB disk is observed due to a mixing of Keplerian rotation of the CB disk, the infall and outflow gas. The streaming gas accreting from the CB ring toward the CS disks and possible outflows are also identified and resolved. The SO emission is found to be at the bases of the streaming shocks. Our results suggest that the UY Aur system is undergoing an active accretion phase from the CB disk to the CS disks. The UY Aur B might also be a binary system, making the UY Aur a triple system.

  5. Comparative investigation of the energetic ion spectra comprising the magnetospheric ring currents of the solar system.

    PubMed

    Mauk, B H

    2014-12-01

    Investigated here are factors that control the intensities and shapes of energetic ion spectra that make up the ring current populations of the strongly magnetized planets of the solar system, specifically those of Earth, Jupiter, Saturn, Uranus, and Neptune. Following a previous and similar comparative investigation of radiation belt electrons, we here turn our attention to ions. Specifically, we examine the possible role of the differential ion Kennel-Petschek limit, as moderated by Electromagnetic Ion Cyclotron (EMIC) waves, as a standard for comparing the most intense ion spectra within the strongly magnetized planetary magnetospheres. In carrying out this investigation, the substantial complexities engendered by the very different ion composition distributions of these diverse magnetospheres must be addressed, given that the dispersion properties of the EMIC waves are strongly determined by the ion composition of the plasmas within which the waves propagate. Chosen for comparison are the ion spectra within these systems that are the most intense observed, specifically at 100 keV and 1 MeV. We find that Earth and Jupiter are unique in having their most intense ion spectra likely limited and sculpted by the Kennel-Petschek process. The ion spectra of Saturn, Uranus, and Neptune reside far below their respective limits and are likely limited by interactions with gas and dust (Saturn) and by the absence of robust ion acceleration processes (Uranus and Neptune). Suggestions are provided for further testing the efficacy of the differential Kennel-Petschek limit for ions using the Van Allen Probes.

  6. Vascular ring

    MedlinePlus

    ... with aberrant subclavian and left ligamentum ateriosus; Congenital heart defect - vascular ring; Birth defect heart - vascular ring ... accounts for less than 1% of all congenital heart problems. The condition occurs as often in males ...

  7. Neptune's rings

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This 591-second exposure of the rings of Neptune were taken with the clear filter by the Voyager 2 wide-angle camera. The two main rings are clearly visible and appear complete over the region imaged. Also visible in this image is the inner faint ring and the faint band which extends smoothly from the ring roughly halfway between the two bright rings. Both of these newly discovered rings are broad and much fainter than the two narrow rings. The bright glare is due to over-exposure of the crescent on Neptune. Numerous bright stars are evident in the background. Both bright rings have material throughout their entire orbit, and are therefore continuous. The Voyager Mission is conducted by JPL for NASA's Office of Space Science and Applications.

  8. The Ring System of Saturn as Seen by Cassini-VIMS (Invited)

    NASA Astrophysics Data System (ADS)

    Filacchione, G.; Ciarniello, M.; Capaccioni, F.

    2015-08-01

    Since 2004 the Visual and Infrared Mapping Spectrometer (VIMS) aboard Cassini has acquired numerous hyperspectral mosaics in the 0.35-5.1 μm spectral range of Saturn's main rings in very different illumination and viewing geometries. These observations have allowed us to infer the ring particles physical properties and composition: water ice abundance is estimated through the 1.25-1.5-2.0 μm band depths, chromophores distribution is derived from visible spectral slopes while organic material is traced by the aliphatic compounds signature at 3.42 μm which appears stronger on CD and C ring than on A-B rings (Filacchione et al., 2014). Observed reflectance spectra are fitted with a spectrophotometric model based on Montecarlo ray-tracing with the scope to infer particles composition while disentangling photometric effects (caused by multiple scattering, opposition surge and forward scattering) which depend on illumination/viewing geometries. Spectral bond albedo for different regions of the rings has been best-fitted using Hapke's radiative transfer modeling (Ciarniello et al, 2011) by choosing different mixtures of water ice, tholin, and amorphous carbon particles populations. While tholin distribution seems to be fairly constant across the rings, the amorphous carbon appears anti-correlated with optical depth. Moreover, dark material contamination is less effective on densest regions, where the more intense rejuvenation processes occur, in agreement with the ballistic transport theory (Cuzzi and Estrada,1998). Finally, the 3.6 μm continuum peak wavelength is used to infer particles temperature, which is anti-correlated with the albedo and the optical depth (tau): low-albedo/low-tau C ring and CD have higher temperatures than A-B rings where albedo and tau are high. This trend matches direct temperature measurements by CIRS (Spilker et al., 2013).

  9. New Psychoactive Substances: Chemistry, Pharmacology, Metabolism, and Detectability of Amphetamine Derivatives With Modified Ring Systems.

    PubMed

    Welter-Luedeke, Jessica; Maurer, Hans H

    2016-02-01

    In recent years, new amphetamine derivatives with modified ring systems were sold and consumed as new drugs of abuse. They belong together with other new drugs of abuse classes to the so-called new psychoactive substances (NPS). The chemistry, pharmacology, toxicology, metabolism, and toxicokinetics are shortly discussed of camfetamine, 3 methylphenyl-amphetamines (2-MA, 3-MA, and 4-MA), 2-methiopropamine (2-MPA), and 5-(2-aminopropyl)benzofuran (5-APB), 6-(2-aminopropyl)benzofuran (6-APB, so-called "benzofury") and their N-methyl derivatives 5-MAPB and 6-MAPB. Only a rough assessment of the pharmacology and toxicology NPS can be performed in most cases using published data of analogs, trip reports, and described clinical cases. Accordingly, they all act more or less as central nervous stimulants mainly by increasing the concentration of the neurotransmitters noradrenaline, dopamine, and serotonin (5-HT) by inducing their release and reuptake inhibition. Thus, the acute toxicity is associated with the sympathomimetic effects, such as mydriasis, hyperthermia, hypertension, tachycardia, insomnia, and anxiety. With the exception of 5- and 6-APB, these NPS were extensively metabolized by N-demethylation and/or aromatic hydroxylation catalyzed by various cytochrome P450 isoenzymes followed by partial glucuronidation and/or sulfation. For urinalysis, the unchanged drugs and/or the nor-metabolites are the main targets.

  10. Pyrrolo[2,3-h]quinolinones: a new ring system with potent photoantiproliferative activity.

    PubMed

    Barraja, Paola; Diana, Patrizia; Montalbano, Alessandra; Dattolo, Gaetano; Cirrincione, Girolamo; Viola, Giampietro; Vedaldi, Daniela; Dall'Acqua, Francesco

    2006-12-15

    A new class of compounds, the pyrrolo[2,3-h]quinolin-2-ones, nitrogen isosters of the angular furocoumarin Angelicin, was synthesized with the aim of obtaining new photochemotherapeutic agents with increased antiproliferative activity and lower undesired toxic effects than the lead compound. Two synthetic pathways were approached to allow the isolation both of the dihydroderivatives 10-17 and of the aromatic ring system 23. Compounds 10-17 showed a remarkable phototoxicity and a great UVA dose dependence reaching IC(50) values at submicromolar level. Intracellular localization of these compounds has been evaluated by means of fluorescence microscopy using tetramethylrhodamine methyl ester and acridine orange, which are specific fluorescent probes for mitochondria and lysosomes, respectively. A weak co-staining was observed with mitochondrial stain, whereas a specific localization in lysosomes was observed. Studies directed to elucidate the mode of action of this series of compounds revealed that they do not intercalate with DNA and do not induce photodamage to the macromolecule. On the contrary, they induce significative photodamage to lipids and proteins.

  11. Understanding the Dynamical Evolution of the Earth Radiation Belt and Ring Current Coupled System

    NASA Astrophysics Data System (ADS)

    Shprits, Yuri; Usanova, Maria; Kellerman, Adam; Drozdov, Alexander

    2016-07-01

    Modeling and understanding the ring current and radiation belt-coupled system has been a grand challenge since the beginning of the space age. In this study we show long-term simulations with a 3D Versatile Electron Radiation Belt (VERB) code of modeling the radiation belts with boundary conditions derived from observations around geosynchronous orbit. Simulations can reproduce long term variations of the electron radiation belt fluxes and show the importance of local acceleration, radial diffusion, loss to the atmosphere and loss to the magnetopause. We also present 4D VERB simulations that include convective transport, radial diffusion, pitch angle scattering and local acceleration. VERB simulations show that the lower energy inward transport is dominated by the convection and higher energy transport is dominated by the diffusive radial transport. We also show that at energies of 100s of keV, a number of processes work simultaneously, including convective transport, radial diffusion, local acceleration, loss to the loss cone and loss to the magnetopause. The results of the simulation of the March 2013 storm are compared with Van Allen Probes observations.

  12. X-ray BPM-based feedback system at the APS storage ring

    SciTech Connect

    Singh, O.; Erwin, L.; Decker, G.; Laird, R.; Lenkszus, F.

    2000-05-17

    At the Advanced Photon Source (APS) storage ring, the X-ray beam position monitors (X-BPMs) measure accurate photon position down to the submicron level. This level of stable measurement has been possible due to (1) superior thermal insulation and vibration damping of the X-ray BPM support structure, (2) minimal dependence on the bunch pattern and intensity variations, and (3) use of ultrastable preamplifiers and processing electronics. A new X-BPM interface is under development and will be discussed here. This interface will be integrated into the existing rf-based orbit feedback systems. To study preliminary results, an experimental X-BPM orbit feedback set-up was developed and implemented in one of the bending magnet beamlines. The results from this set-up are encouraging. For an operational fill, a typical orbit drift of 30 microns (at X-ray BPMs) has been reduced to less than 5 microns. The fill-to-fill photon orbit reproducibility has been improved from 75 microns to less than 10 microns.

  13. Evolution of the rf systems layout for the SSC collider rings

    SciTech Connect

    Schaffer, G.

    1993-10-01

    This note contains information on the results of ongoing reviews concerning the basic design of the 360-MHz rf systems for the 2 {times} 20 TeV Superconducting Super Collider (SSC). For generation of 20-MV peak voltage per ring, with proton beams of 2 {times} 70 mA, several versions have been investigated: Version A (baseline design and modified baseline): 2 {times} 8 five-cell normalconducting cavities; Version B: 2 {times} 24 single-cell normalconducting cavities; and Version C: 2 {times} 8 or 2 {times} 10 single-cell superconducting cavities. For reasons of easier High Order Mode (HOM) damping, multicell cavities have been found inferior in performance when compared to single cells. Superconducting cavities have been found superior in handling transient beam loading when compared to normalconducting cavities. A threefold higher voltage, and a reduced R/Q value of superconducting cells lead to a ninefold increase in stored electromagnetic energy which, by the same factor, reduces the speed of phase changes originating from notches in the circulating beams. The theoretical possibility to operate superconducting cavities half-detuned in order to supply reactive power to the beam may also lead to considerable savings in overall power consumption. On the other hand, many challenges are involved with the use of superconducting cavities, such as the delicacy of the superconductive state, the complexity of cryostat design and operation, tuning requirements, sensitivity to vibration, and other issues.

  14. Heteroditopic ligands based on ferrocenyl benzimidazoles fused to an additional diaza heterocyclic ring system.

    PubMed

    Alfonso, María; Sola, Antonia; Caballero, Antonio; Tárraga, Alberto; Molina, Pedro

    2009-11-21

    The synthesis of ferrocene-based heteroditopic receptors in which the ferrocene moiety is attached to an imidazo[4,5-e]benzothiadiazole or imidazo[4,5-f]quinoxaline is reported. These nitrogen-rich ferrocene derivatives show remarkable ion-sensing properties because of the presence of the redox active ferrocene unit and the polyazaheteroaromatic ring systems which act as a dual binding site for anions and metal cations. They display an anodic shift of the oxidation wave (DeltaE(1/2) = 67-200 mV) upon complexation with metal cations and a strong cathodic shift (DeltaE(1/2) = -82 to -100 mV) in the presence of F(-) and HP(2)O(7)(3-) anions. For the Zn(2+), Cd(2+), Hg(2+) and Pb(2+) metal cations tested, the change in the absorption spectra is accompanied by a dramatic colour change which allows the potential for "naked eye" detection.

  15. Comparative investigation of the energetic ion spectra comprising the magnetospheric ring currents of the solar system

    PubMed Central

    Mauk, B H

    2014-01-01

    Investigated here are factors that control the intensities and shapes of energetic ion spectra that make up the ring current populations of the strongly magnetized planets of the solar system, specifically those of Earth, Jupiter, Saturn, Uranus, and Neptune. Following a previous and similar comparative investigation of radiation belt electrons, we here turn our attention to ions. Specifically, we examine the possible role of the differential ion Kennel-Petschek limit, as moderated by Electromagnetic Ion Cyclotron (EMIC) waves, as a standard for comparing the most intense ion spectra within the strongly magnetized planetary magnetospheres. In carrying out this investigation, the substantial complexities engendered by the very different ion composition distributions of these diverse magnetospheres must be addressed, given that the dispersion properties of the EMIC waves are strongly determined by the ion composition of the plasmas within which the waves propagate. Chosen for comparison are the ion spectra within these systems that are the most intense observed, specifically at 100 keV and 1 MeV. We find that Earth and Jupiter are unique in having their most intense ion spectra likely limited and sculpted by the Kennel-Petschek process. The ion spectra of Saturn, Uranus, and Neptune reside far below their respective limits and are likely limited by interactions with gas and dust (Saturn) and by the absence of robust ion acceleration processes (Uranus and Neptune). Suggestions are provided for further testing the efficacy of the differential Kennel-Petschek limit for ions using the Van Allen Probes. PMID:26167438

  16. Jupiter's Ring Halo

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A mosaic of four images taken through the clear filter (610 nanometers) of the solid state imaging (CCD) system aboard NASA's Galileo spacecraft on November 8, 1996, at a resolution of approximately 46 kilometers (km) per picture element (pixel) along the rings; however, because the spacecraft was only about 0.5 degrees above the ring plane, the image is highly foreshortened in the vertical direction. The images were obtained when Galileo was in Jupiter's shadow peering back toward the Sun; the ring was approximately 2,300,000 kilometers (km) away. The arc on the far right of the image is produced by sunlight scattered by small particles comprising Jupiter's upper atmospheric haze. The ring also efficiently scatters light, indicating that much of its brightness is due to particles that are microns or less in diameter. Such small particles are believed to have human-scale lifetimes, i.e., very brief compared to the solar system's age.

    Jupiter's ring system is composed of three parts -- a flat main ring, a lenticular halo interior to the main ring, and the gossamer ring, which lies exterior to the main ring. The near and far arms of Jupiter's main ring extend horizontally across the mosaic, joining together at the ring's ansa, on the far left side of the figure. The near arm of the ring appears to be abruptly truncated close to the planet, at the point where it passes into Jupiter's shadow.

    A faint mist of particles can be seen above and below the main rings; this vertically extended, toroidal 'halo' is unusual in planetary rings, and is probably caused by electromagnetic forces which can push small grains out of the ring plane. Halo material is present across this entire image, implying that it reaches more than 27,000 km above the ring plane. Because of shadowing, the halo is not visible close to Jupiter in the lower right part of the mosaic. In order to accentuate faint features in the image, different brightnesses are shown through color, with the brightest

  17. Lab-on-a-chip bio/chemical sensing system based on the liquid core optical ring resonator

    NASA Astrophysics Data System (ADS)

    White, Ian M.; Suter, Jonathan D.; Zhu, Hongying; Oveys, Hesam; Brewington, Lee; Gohring, John; Fan, Xudong

    2007-04-01

    The liquid core optical ring resonator (LCORR) sensor is a newly developed capillary-based ring resonator that integrates microfluidics with photonic sensing technology. The circular cross-section of the capillary forms a ring resonator that supports whispering gallery modes (WGM), which interact with the sample as it passes through the capillary. As in previous ring resonator sensor implementations, the interaction between the WGM evanescent field and the sample enables label-free detection. With a prototype of an LCORR sensor, we have achieved a refractive index detection limit of 10-6 RIU and a detection limit for protein of 2 pg/mm2. Several engineering developments have been accomplished as well, including a thermal noise characterization, a thermal stabilization implementation, integration of the LCORR with a planar waveguide array, and electro-kinetic sample delivery. In the near future, the LCORR will be integrated into a dense 2-dimensional sensing array by integrating multiple capillaries with a chip-based waveguide array. This lab-on-a-chip sensing system will have a number of applications, including environmental sensing for defense purposes, disease diagnostics for medical purposes, and as a lab tool for analytical chemistry and molecular analysis.

  18. Saturn's Rings, the Yarkovsky Effects, and the Ring of Fire

    NASA Technical Reports Server (NTRS)

    Rubincam, David Parry

    2004-01-01

    The dimensions of Saturn's A and B rings may be determined by the seasonal Yarkovsky effect and the Yarkovsky-Schach effect; the two effects confine the rings between approximately 1.68 and approximately 2.23 Saturn radii, in reasonable agreement with the observed values of 1.525 and 2.267. The C ring may be sparsely populated because its particles are transients on their way to Saturn; the infall may create a luminous Ring of Fire around Saturn's equator. The ring system may be young: in the past heat flow from Saturn's interior much above its present value would not permit rings to exist.

  19. Vortex rings

    NASA Technical Reports Server (NTRS)

    Shariff, Karim; Leonard, Anthony

    1992-01-01

    The vortex-ring problem in fluid mechanics is examined generally in terms of formation, the steady state, the duration of the rings, and vortex interactions. The formation is studied by examining the generation of laminar and turbulent vortex rings and their resulting structures with attention given to the three stages of laminar ring development. Inviscid dynamics is addressed to show how core dynamics affects overall ring motion, and laminar vortex structures are described in two dimensions. Viscous and inviscid structures are related in terms of 'leapfrogging', head-on collisions, and collisions with a no-slip wall. Linear instability theory is shown to successfully describe observational data, although late stages in the breakdown are not completely understood. This study of vortex rings has important implications for key aerodynamic issues including sound generation, transport and mixing, and vortex interactions.

  20. Redesign of solid rocket booster/external tank attachment ring for the space transportation system

    NASA Technical Reports Server (NTRS)

    Mccomb, Harvey G., Jr. (Compiler)

    1987-01-01

    An improved design concept is presented for the Space Shuttle solid rocket booster (SRB)/external tank (ET) attachment ring structural component. This component picks up three struts which attach the aft end of each SRB to the ET. The concept is a partial ring with carefully tapered ends to distribute fastener loads safely into the SRB. Extensive design studies and analyses were performed to arrive at the concept. Experiments on structural elements were performed to determine material strength and stiffness characteristics. Materials and fabrication studies were conducted to determine acceptable tolerances for the design concept. An overview is provided of the work along with conclusions and major recommendations.

  1. Merging tree ring chronologies and climate system model simulated temperature by optimal interpolation algorithm in North America

    NASA Astrophysics Data System (ADS)

    Chen, Xin; Xing, Pei; Luo, Yong; Zhao, Zongci; Nie, Suping; Huang, Jianbin; Wang, Shaowu; Tian, Qinhua

    2015-04-01

    A new dataset of annual mean surface temperature has been constructed over North America in recent 500 years by performing optimal interpolation (OI) algorithm. Totally, 149 series totally were screened out including 69 tree ring width (MXD) and 80 tree ring width (TRW) chronologies are screened from International Tree Ring Data Bank (ITRDB). The simulated annual mean surface temperature derives from the past1000 experiment results of Community Climate System Model version 4 (CCSM4). Different from existing research that applying data assimilation approach to (General Circulation Models) GCMs simulation, the errors of both the climate model simulation and tree ring reconstruction were considered, with a view to combining the two parts in an optimal way. Variance matching (VM) was employed to calibrate tree ring chronologies on CRUTEM4v, and corresponding errors were estimated through leave-one-out process. Background error covariance matrix was estimated from samples of simulation results in a running 30-year window in a statistical way. Actually, the background error covariance matrix was calculated locally within the scanning range (2000km in this research). Thus, the merging process continued with a time-varying local gain matrix. The merging method (MM) was tested by two kinds of experiments, and the results indicated standard deviation of errors can be reduced by about 0.3 degree centigrade lower than tree ring reconstructions and 0.5 degree centigrade lower than model simulation. During the recent Obvious decadal variability can be identified in MM results including the evident cooling (0.10 degree per decade) in 1940-60s, wherein the model simulation exhibit a weak increasing trend (0.05 degree per decade) instead. MM results revealed a compromised spatial pattern of the linear trend of surface temperature during a typical period (1601-1800 AD) in Little Ice Age, which basically accorded with the phase transitions of the Pacific decadal oscillation (PDO) and

  2. Single bunch injection system for storage ring FEL using an rf photoinjector

    NASA Astrophysics Data System (ADS)

    O'Shea, P. G.; Lancaster, J. A.; Madey, J. M. J.; Sachtschale, R.; Jones, R.

    1997-05-01

    RF photoinjectors have gained acceptance as the source of choice for high-brightness electron accelerators, but have been quite expensive to build and difficult to operate. In this paper we describe the successful operation of an inexpensive, simple and reliable rf photoinjector suitable for single bunch injection into storage rings. For optimum storage ring FEL and Compton Backscatter performance, we require that the electrons be injected to specified ring rf buckets and no others. The injector-linac electron gun is a single-cell s-band rf gun with a LaB6 cathode. The gun is followed by an a-magnet momentum filter and buncher. The LaB6 cathode can be operated in a pure thermionic mode, a laser switched photoemission mode, or in a combined mode. The laser is a near-UV TEA nitrogen laser with a 600 ps pulse, and 0-50 Hz repetition rate. We routinely inject 0.1 nC bunches at 270 MeV. The ratio of charge in the primary ring bucket to that in the other buckets is better than 1000.

  3. The gravito-electrodynamics of charged dust in planetary ring systems

    NASA Technical Reports Server (NTRS)

    Mendis, D. A.; Hill, J. R.; Northrop, T. G.

    1982-01-01

    The dynamics of micron and submicron sized dust grains moving under the combined influence of planetary gravitation and the electromagnetic forces within the corotating regions of planetary magnetospheres are discussed. Magnetogravitational capture of charged grains in planetary rings is outlined. The adiabatic motion of charged dust is reviewed.

  4. On the role of a coumarin derivative for sensing applications: Nucleotide identification using a micellar system.

    PubMed

    Bettoschi, Alexandre; Ceglie, Andrea; Lopez, Francesco; Meli, Valeria; Murgia, Sergio; Tamburro, Manuela; Caltagirone, Claudia; Cuomo, Francesca

    2016-09-01

    The recognition of nucleotides is of crucial importance because they are the basic constituents of nucleic acids. The present study is focused on the selective interaction between a novel amphiphilic fluorophore containing coumarin and imidazole, CI (1-methyl-3-(12-((2-oxo-2H-chromen-7-yl)oxy)dodecyl)-1H-imidazol-3-ium bromide), and different nucleotide-monophosphates (NMPs). It was supposed that the solubilization of the low water soluble CI in a micelle system of hexadecyltrimethylammonium chloride (CTAC) would make the coumarin moiety of CI available to the interaction with the water-soluble NMPs. Changes in CTAC critical micelle concentration suggested that CI strongly interacted with the host cationic surfactant, thus forming a positively charged interface enriched with coumarin able to interact with the anionic NMPs. Steady-state fluorescence quenching revealed that CI/CTAC system was capable of distinguish between purine- and pyrimidine-based nucleotides. A modified Stern-Volmer equation permitted the use of a quenching model that accounted for the possible interactions between the micelles and the nucleotides. The data analysis allowed calculating selective parameters that differentiated according to the type of nucleotide either at 25 or 50°C. Our results established the utility of the novel coumarin derivative fluorophore, supported by the simple and suitable micellar systems, as a tool for DNA sensing applications.

  5. Simulating the Smallest Ring World of Chariklo

    NASA Astrophysics Data System (ADS)

    Michikoshi, Shugo; Kokubo, Eiichiro

    2017-03-01

    A ring system consisting of two dense narrow rings has been discovered around Centaur Chariklo. The existence of these rings around a small object poses various questions about their origin, stability, and lifetime. In order to understand the nature of Chariklo’s rings, we perform global N-body simulations of the self-gravitating collisional particle rings for the first time. We find that Chariklo should be denser than the ring material in order to avoid the rapid diffusion of the rings. If Chariklo is denser than the ring material, fine spiral structures called self-gravity wakes occur in the inner ring. These wakes accelerate the viscous spreading of the ring significantly and typically occur on timescales of about 100 {years} for m-sized ring particles, which is considerably shorter than the timescales suggested in previous studies. The existence of these narrow rings implies smaller ring particles or the existence of shepherding satellites.

  6. Ballistic transport in planetary ring systems due to particle erosion mechanisms. II - Theoretical models for Saturn's A- and B-ring inner edges

    NASA Technical Reports Server (NTRS)

    Durisen, Richard H.; Bode, Paul W.; Cuzzi, Jeffrey N.; Cederbloom, Steven E.; Murphy, Brian W.

    1992-01-01

    The present numerical simulations and analytic arguments show that many of the common morphological features of the Saturn A- and B-ring inner-edge regions are due to 'ballistic transport', or the net radial transport of mass and angular momentum generated by exchanges of meteoroid impact ejecta. It is suggested that the observed 100-km undulatory structure of the inner B-ring arises from ballistic transport echoing of the inner edge. A strongly prograde ejecta-distribution function is used to fit the edge-region features.

  7. Cavity ring-down spectroscopy (CRDS) system for measuring atmospheric mercury using differential absorption

    NASA Astrophysics Data System (ADS)

    Pierce, A.; Obrist, D.; Moosmuller, H.; Moore, C.

    2012-04-01

    Atmospheric elemental mercury (Hg0) is a globally pervasive element that can be transported and deposited to remote ecosystems where it poses — particularly in its methylated form — harm to many organisms including humans. Current techniques for measurement of atmospheric Hg0 require several liters of sample air and several minutes for each analysis. Fast-response (i.e., 1 second or faster) measurements would improve our ability to understand and track chemical cycling of mercury in the atmosphere, including high frequency Hg0 fluctuations, sources and sinks, and chemical transformation processes. We present theory, design, challenges, and current results of our new prototype sensor based on cavity ring-down spectroscopy (CRDS) for fast-response measurement of Hg0 mass concentrations. CRDS is a direct absorption technique that implements path-lengths of multiple kilometers in a compact absorption cell using high-reflectivity mirrors, thereby improving sensitivity and reducing sample volume compared to conventional absorption spectroscopy. Our sensor includes a frequency-doubled, dye-laser emitting laser pulses tunable from 215 to 280 nm, pumped by a Q-switched, frequency tripled Nd:YAG laser with a pulse repetition rate of 50 Hz. We present how we successfully perform automated wavelength locking and stabilization of the laser to the peak Hg0 absorption line at 253.65 nm using an external isotopically-enriched mercury (202Hg0) cell. An emphasis of this presentation will be on the implementation of differential absorption measurement whereby measurements are alternated between the peak Hg0 absorption wavelength and a nearby wavelength "off" the absorption line. This can be achieved using a piezo electric tuning element that allows for pulse-by-pulse tuning and detuning of the laser "online" and "offline" of the Hg absorption line, and thereby allows for continuous correction of baseline extinction losses. Unexpected challenges with this approach included

  8. Earth: A Ringed Planet?

    NASA Astrophysics Data System (ADS)

    Hancock, L. O.; Povenmire, H.

    2010-12-01

    Among the most beautiful findings of the Space Age have been the discoveries of planetary rings. Not only Saturn but also Jupiter, Uranus and Neptune have rings; Saturn’s ring system has structures newly discovered; even Saturn's moon Rhea itself has a ring. All these are apparently supplied by material from the planetary moons (Rhea's ring by Rhea itself). The question naturally arises, why should the Earth not have a ring, and on the other hand, if it does, why has it not been observed? No rings have yet been observed in the inner solar system, but after all, rings in the inner solar system might simply tend to be fainter and more transient than those of the outer solar system: the inner solar system is more affected by the solar wind, and the Sun’s perturbing gravitational influence is greater. J.A. O’Keefe first suggested (1980) that Earth might have a ring system of its own. An Earth ring could account for some climate events. O’Keefe remarked that formation or thickening of a ring system in Earth’s equatorial plane could drive glaciation by deepening the chill of the winter hemisphere. (It is very well established that volcanic dust is an effective agent for the extinction of sunlight; this factor can be overwhelmingly apparent in eclipse observations.) O’Keefe died in 2000 and the speculation was not pursued, but the idea of an Earth ring has a prima facie reasonableness that calls for its renewed consideration. The program of this note is to hypothesize that, as O’Keefe proposed: (a) an Earth ring system exists; (b) it affects Earth's weather and climate; (c) the tektite strewn fields comprise filaments of the ring fallen to Earth's surface on various occasions of disturbance by comets or asteroids. On this basis, and drawing on the world's weather records, together with the Twentieth Century Reanalysis by NCEP/CIRES covering the period 1870-2010 and the geology of the tektite strewn fields, we herein propose the hypothesized Earth ring

  9. A family of ring system-based structural fragments for use in structure-activity studies: database mining and recursive partitioning.

    PubMed

    Nilakantan, Ramaswamy; Nunn, David S; Greenblatt, Lynne; Walker, Gary; Haraki, Kevin; Mobilio, Dominick

    2006-01-01

    In earlier work from our laboratory, we have described the use of the ring system and ring scaffold as descriptors. We showed that these descriptors could be used for fast compound clustering, novelty determination, compound acquisition, and combinatorial library design. Here we extend the concept to a whole family of structural descriptors with the ring system as the centerpiece. We show how this simple idea can be used to build powerful search tools for mining chemical databases in useful ways. We have also built recursive partition trees using these fragments as descriptors. We will discuss how these trees can help in analyzing complex structure-activity data.

  10. Macroscopic anatomy of the ringed seal [Pusa (Phoca) hispida] lower respiratory system.

    PubMed

    Smodlaka, H; Henry, R W; Reed, R B

    2009-06-01

    This investigation serves to document the normal anatomical features of the lower respiratory tract of the ringed seal [Pusa (phoca) hispida]. Evaluation of embalmed specimens and tracheobronchial casts showed that the right lung of this seal consists of four lobes while the left has only three lobes. The ventral margins of the lungs do not reach the sternum causing them to form the boundary of the broad recessus costomediastinalis. Lung lobation corresponds with bronchial tree division. Pulmonary venous drainage includes right and left common veins draining ipsilateral cranial and middle lung lobes, and one common caudal vein draining both caudal lobes and the accessory lobe. The right and left pulmonary arteries divide into cranial and caudal branches at the level of the principal bronchus. The ringed seal has three tracheobronchial lymph nodes. The trachea has an average of 87 cartilages that exhibit a pattern of random anastomoses between adjacent rings. The trachea exhibits to a small degree the dorsoventrally flattened pattern that is described in other pinnipeds. The tracheal diameter is smaller than that of the canine.

  11. Synthesis of the new ring system bispyrido[4',3':4,5]pyrrolo [1,2-a:1',2'-d]pyrazine and its deaza analogue.

    PubMed

    Parrino, Barbara; Spanò, Virginia; Carbone, Anna; Barraja, Paola; Diana, Patrizia; Cirrincione, Girolamo; Montalbano, Alessandra

    2014-08-29

    Derivatives of the new ring systems bispyrido[4',3':4,5]pyrrolo[1,2-a:1',2'-d] pyrazine-6,13-dione and its deaza analogue pyrido[4'',3'':4',5']pyrrolo-[1',2':4,5]pyrazino [1,2-a]indole-6,13-dione were conveniently synthesized through a four-step sequence. Symmetrical derivatives of the former ring system were obtained through self condensation. On the other hand, condensation of 6-azaindole carboxylic acid with indole 2-carboxylic acid afforded the deaza analogue ring system. Derivatives of the title ring system were tested by the National Cancer Institute (Bethesda, MD, USA) and four of them exhibited modest activity against MCF7 (a breast cancer cell line) and/or UO-31 (a renal cancer cell line).

  12. Variable diameter CO2 laser ring-cutting system adapted to a zoom microscope for applications on polymer tapes.

    PubMed

    Förster, Erik; Bohnert, Patrick; Kraus, Matthias; Kilper, Roland; Müller, Ute; Buchmann, Martin; Brunner, Robert

    2016-11-20

    This paper presents the conception and implementation of a variable diameter ring-cutting system for a CO2 laser with a working wavelength of 10.6 μm. The laser-cutting system is adapted to an observation zoom microscope for combined use and is applicable for the extraction of small circular areas from polymer films, such as forensic adhesive tapes in a single shot. As an important characteristic for our application, the variable diameter ring-cutting system provides telecentricity in the target area. Ring diameters are continuously tunable between 500 μm and 2 mm. A minimum width of less than 20 μm was found for the ring profile edge. The basic characteristics of the system, including telecentricity, were experimentally evaluated and demonstrated by cutting experiments on different polymer tapes and further exemplary samples.

  13. Jupiter's Gossamer Rings Explained.

    NASA Astrophysics Data System (ADS)

    Hamilton, D. P.

    2003-05-01

    Over the past several years, Galileo measurements and groundbased imaging have drastically improved our knowledge of Jupiter's faint ring system. We now recognize that the ring consists of four components: a main ring 7000km wide, whose inner edge blossoms into a vertically-extended halo, and a pair of more tenuous Gossamer rings, one associated with each of the small moons Thebe and Amalthea. When viewed edge on, the Gossamer rings appear as diaphanous disks whose thicknesses agree with the vertical excursions of the inclined satellites from the equatorial plane. In addition, the brightness of each Gossamer ring drops off sharply outside the satellite orbits. These correlations allowed Burns etal (1999, Science, 284, 1146) to argue convincingly that the satellites act as sources of the dusty ring material. In addition, since most material is seen inside the orbits of the source satellites, an inwardly-acting dissipative force such as Poynting-Robertson drag is implicated. The most serious problem with this simple and elegant picture is that it is unable to explain the existence of a faint swath of material that extends half a jovian radius outward from Thebe. A key constraint is that this material has the same thickness as the rest of the Thebe ring. In this work, we identify the mechanism responsible for the outward extension: it is a shadow resonance, first investigated by Horanyi and Burns (1991, JGR, 96, 19283). When a dust grain enters Jupiter's shadow, photoelectric processes shut down and the grain's electric charge becomes more negative. The electromagnetic forces associated with the varying charge cause periodic oscillations in the orbital eccentricity and semimajor axis as the orbital pericenter precesses. This results in a ring which spreads both inward and outward of its source satellite while preserving its vertical thickness - just as is observed for the Thebe ring. Predictions of the model are: i) gaps of micron-sized material interior to Thebe and

  14. Design and system integration of the superconducting wiggler magnets for the Compact Linear Collider damping rings

    NASA Astrophysics Data System (ADS)

    Schoerling, Daniel; Antoniou, Fanouria; Bernhard, Axel; Bragin, Alexey; Karppinen, Mikko; Maccaferri, Remo; Mezentsev, Nikolay; Papaphilippou, Yannis; Peiffer, Peter; Rossmanith, Robert; Rumolo, Giovanni; Russenschuck, Stephan; Vobly, Pavel; Zolotarev, Konstantin

    2012-04-01

    To achieve high luminosity at the collision point of the Compact Linear Collider (CLIC), the normalized horizontal and vertical emittances of the electron and positron beams must be reduced to 500 and 4 nm before the beams enter the 1.5 TeV linear accelerators. An effective way to accomplish ultralow emittances with only small effects on the electron polarization is using damping rings operating at 2.86 GeV equipped with superconducting wiggler magnets. This paper describes a technical design concept for the CLIC damping wigglers.

  15. Transition between different quantum states in a mesoscopic system: The superconducting ring

    SciTech Connect

    Horane, E.M.; Castro, J.I.; Buscaglia, G.C.; Lopez, A.

    1996-04-01

    We investigate the thermodynamic properties of a superconducting ring, both analytically and numerically, relying upon the Ginzburg-Landau theory. We find that modulated solutions for the order parameter play a role in describing the thermodynamic transitions between consecutive modes of uniform order parameter, associated with different quantum numbers. Exact expressions for these solutions are given in terms of elliptic functions. We identify the family of energy extrema which, being saddle points of the energy in the functional space of the distributions of the order parameter, represent the energy barrier to be overcome for transitions between different solutions. {copyright} {ital 1996 The American Physical Society.}

  16. The Enceladus Ring

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] The Enceladus Ring (labeled)

    This excellent view of the faint E ring -- a ring feature now known to be created by Enceladus -- also shows two of Saturn's small moons that orbit within the ring, among a field of stars in the background.

    The E ring extends from three to eight Saturn radii -- about 180,000 kilometers (118,000 miles) to 482,000 kilometers (300,000 miles). Its full extent is not visible in this view.

    Calypso (22 kilometers, or 14 miles across) and Helene (32 kilometers, or 20 miles across) orbit within the E ring's expanse. Helene skirts the outer parts of the E ring, but here it is projected in front of a region deeper within the ring.

    Calypso and Helene are trojan satellites, or moons that orbit 60 degrees in front or behind a larger moon. Calypso is a Tethys trojan and Helene is a trojan of Dione.

    An interesting feature of note in this image is the double-banded appearance of the E-ring, which is created because the ring is somewhat fainter in the ringplane than it is 500-1,000 kilometers (300-600 miles) above and below the ringplane. This appearance implies that the particles in this part of the ring have nonzero inclinations (a similar affect is seen in Jupiter's gossamer ring). An object with a nonzero inclination does not orbit exactly at Saturn's ringplane. Instead, its orbit takes it above and below the ringplane. Scientists are not entirely sure why the particles should have such inclinations, but they are fairly certain that the reason involves Enceladus.

    One possible explanation is that all the E ring particles come from the plume of icy material that is shooting due south out of the moon's pole. This means all of the particles are created with a certain velocity out of the ringplane, and then they orbit above and below that plane.

    Another possible explanation is that Enceladus produces particles with a range of speeds, but the moon gravitationally

  17. Comparing the performance of multiple imaging systems with Fabry-Perot interferometers, concentric ring masks, and diffractive multifocal lenses

    NASA Astrophysics Data System (ADS)

    Sedukhin, Andrey G.

    2007-06-01

    Based on the conditions of alowable angular sampling of interfering waves, monochromatic multiple imaging systems with replicating spatial-frequency filters in the form of Fabry-Perot Interferometers, concentric ring masks, and diffractive multifocal lenses are compared with each other in their performance. Though these systems are shown to realize the same effect of multiple equidistant imaging, the forms of manifestation of the effect are not identical due to the difference in spectral content of the wave fields produced by the systems. The most perfect systems are found to be those with pure-phase diffractive multifocal lenses. First of all, they benefits from the extremely high total light efficiency and the sharply defined longitudinal localization of the visualized object space defined by the efficient focal depth. This enhances considerably the brightness of reproduced images and decreases their parasitic diffraction dispersion, background noise, and blurring.

  18. Transient electric current through an Aharonov-Bohm ring after switching of a two-level system

    NASA Astrophysics Data System (ADS)

    Tatara, Gen

    2002-05-01

    The response of the electronic current through an Aharonov-Bohm ring after a two-level-system is switched on is calculated perturbatively by use of a nonequilibrium Green function. In the ballistic case the amplitude of the Aharonov-Bohm oscillation is shown to decay to a new equilibrium value due to scattering into other electronic states. The relaxation of the Altshuler-Aronov-Spivak oscillation in the diffusive case, due to the dephasing effect, is also calculated. The time scale of the relaxation is determined by characteristic relaxation times of the system and the splitting of a two-level-system. The oscillation phase is not affected. Experimental studies of current response would give us direct information about characteristic times of mesoscopic systems.

  19. Toward a noninvasive automatic seizure control system in rats with transcranial focal stimulations via tripolar concentric ring electrodes

    PubMed Central

    Makeyev, Oleksandr; Liu, Xiang; Luna-Munguía, Hiram; Rogel-Salazar, Gabriela; Mucio-Ramirez, Samuel; Liu, Yuhong; Sun, Yan L.; Kay, Steven M.; Besio, Walter G.

    2012-01-01

    Epilepsy affects approximately one percent of the world population. Antiepileptic drugs are ineffective in approximately 30% of patients and have side effects. We are developing a noninvasive, or minimally invasive, transcranial focal electrical stimulation system through our novel tripolar concentric ring electrodes to control seizures. In this study we demonstrate feasibility of an automatic seizure control system in rats with pentylenetetrazole-induced seizures through single and multiple stimulations. These stimulations are automatically triggered by a real-time electrographic seizure activity detector based on a disjunctive combination of detections from a cumulative sum algorithm and a generalized likelihood ratio test. An average seizure onset detection accuracy of 76.14% was obtained for the test set (n = 13). Detection of electrographic seizure activity was accomplished in advance of the early behavioral seizure activity in 76.92% of the cases. Automatically triggered stimulation significantly (p = 0.001) reduced the electrographic seizure activity power in the once stimulated group compared to controls in 70% of the cases. To the best of our knowledge this is the first closed-loop automatic seizure control system based on noninvasive electrical brain stimulation using tripolar concentric ring electrode electrographic seizure activity as feedback. PMID:22772373

  20. Explicitly-correlated ring-coupled-cluster-doubles theory: Including exchange for computations on closed-shell systems

    NASA Astrophysics Data System (ADS)

    Hehn, Anna-Sophia; Holzer, Christof; Klopper, Wim

    2016-11-01

    Random-phase-approximation (RPA) methods have proven to be powerful tools in electronic-structure theory, being non-empirical, computationally efficient and broadly applicable to a variety of molecular systems including small-gap systems, transition-metal compounds and dispersion-dominated complexes. Applications are however hindered due to the slow basis-set convergence of the electron-correlation energy with the one-electron basis. As a remedy, we present approximate explicitly-correlated RPA approaches based on the ring-coupled-cluster-doubles formulation including exchange contributions. Test calculations demonstrate that the basis-set convergence of correlation energies is drastically accelerated through the explicitly-correlated approach, reaching 99% of the basis-set limit with triple-zeta basis sets. When implemented in close analogy to early work by Szabo and Ostlund [36], the new explicitly-correlated ring-coupled-cluster-doubles approach including exchange has the perspective to become a valuable tool in the framework of symmetry-adapted perturbation theory (SAPT) for the computation of dispersion energies of molecular complexes of weakly interacting closed-shell systems.

  1. Commissioning results of the narrow-band beam position monitor system upgrade in the APS storage ring.

    SciTech Connect

    Singh, O.

    1999-04-20

    When using a low emittance storage ring as a high brightness synchrotron radiation source, it is critical to maintain a very high degree of orbit stability, both for the short term and for the duration of an operational fill. A fill-to-fill reproducibility is an additional important requirement. Recent developments in orbit correction algorithms have provided tools that are capable of achieving a high degree of orbit stability. However, the performance of these feedback systems can be severely limited if there are errors in the beam position monitors (BPMs). The present orbit measurement and correction system at the APS storage ring utilizes 360 broad-band-type BPMs that provide turn-by-turn diagnostics and an ultra-stable orbit: < 1.8 micron rms vertically and 4.5 microns rms horizontally in a frequency band of 0.017 to 30 Hz. The effects of beam intensity and bunch pattern dependency on these BPMs have been significantly reduced by employing offset compensation correction. Recently, 40 narrow-band switching-type BPMs have been installed in the APS storage ring, two in each of 20 operational insertion device straight sections, bringing the total number of beam position monitors to 400. The use of narrow-band BPM electronics is expected to reduce sensitivity to beam intensity, bunch pattern dependence, and long-term drift. These beam position monitors are used for orbit correction/feedback and machine protection interlocks for the insertion device beamlines. The commissioning results and overall performance for orbit stability are provided.

  2. A season in Saturn's rings: Cycling, recycling and ring history

    NASA Astrophysics Data System (ADS)

    Esposito, L. W.; Meinke, B. K.; Albers, N.; Sremcevic, M.

    2012-04-01

    Cassini experiments have watched Saturn's ring system evolve before our eyes. Images and occultations show changes and transient events. The rings are a dynamic and complex geophysical system, incompletely modeled as a single-phase fluid. Key Cassini observations: High resolution images show straw, propellers, embedded moonlets, and F ring objects. Multiple UVIS, RSS and VIMS occutlations indicate multimodal ringlet and edge structure, including free and forced modes along with stochastic perturbations that are most likely caused by nearby mass concentrations. Vertical excursions are evident at ring edges and in other perturbed regions. The rings are occasionally hit by meteorites that leave a signature that may last centuries; meteoritic dust pollutes the rings. Temperature, reflectance and transmission spectra are influenced by the dynamical state of the ring particles. Saturn's Equinox 2009: Oblique lighting exposed vertical structure and embedded objects. The rings were the coldest ever. Images inspired new occultation and spectral analysis that show abundant structure in the perturbed regions. The rings are more variable and complex than we had expected prior to this seasonal viewing geometry. Sub-kilometer structure in power spectral analysis: Wavelet analysis shows features in the strongest density waves and at the shepherded outer edge of the B ring. Edges are variable as shown by multiple occultations and occultations of double stars. F ring kittens: 25 features seen in the first 102 occultations show a weak correlation with Prometheus location. We interpret these features as temporary aggregations. Simulation results indicate that accretion must be enhanced to match the kittens' size distribution. Images show that Prometheus triggers the formation of transient objects. Propellers and ghosts: Occulations and images provide evidence for small moonlets in the A, B and C rings. These indicate accretion occurs inside the classical Roche limit. Implications

  3. Ring Enlargement of Three-Membered Boron Heterocycles upon Reaction with Organic π Systems: Implications for the Trapping of Borylenes.

    PubMed

    Krasowska, Małgorzata; Bettinger, Holger F

    2016-07-18

    New low-energy pathways for the reaction between substituted boriranes and borirenes with unsaturated hydrocarbons (ethyne or ethene) were discovered using density functional and coupled cluster theory. The interaction between the π bond of the hydrocarbon and the empty p orbital of the boron center leads to ring expansion of the three-membered to a five-membered boron heterocycle. The reactions are strongly exothermic and have low or even no barriers. They involve intermediates with a pentacoordinate boron center with two hydrocarbon molecules coordinating to boron akin to metal-olefin complexes. These borylene complexes are shallow minima on the potential energy surfaces. But significantly higher barriers for ring formation are computed for 1,5-cyclooctadiene and dibenzocyclooctatetraene complexes of borylenes, making these complexes likely detectable under appropriate experimental conditions. Our computational findings have implications for the interpretation of trapping experiments of thermally generated small borylenes with excess of small π systems. Because of very low barriers for reactions of three-membered boron heterocycles with π systems and the at least locally large excess of the latter under such conditions, formation of five-membered boron heterocycles should be considered.

  4. Flex-gear power transmission system for transmitting EMF between Sun and ring gears

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    1994-01-01

    A plurality of flexible cylindrical members, termed flex-gears and having gear tooth type perimeters are located in an annular space between two concentric rotating gear members, one an inner gear member and the other an outer ring gear member, both of which have mutually facing toothed surfaces which engage the flex-gears. The flex-gears rotate and orbit around the annular space as planetary gears when the inner and outer gear members rotate with respect to one another. Pairs of these elements located in two mutually parallel planes and separated by insulators provide two electrical conductor paths across which an electrical signal source, AC or DC, can be connected and coupled to an electrical device. Alternatively, one set of elements including outer gears segmented into mutually insulated semicircles and inner gears segmented into mutually insulated quadrants can be used.

  5. UHV seal studies for the advanced photon source storage ring vacuum system

    SciTech Connect

    Gonczy, J.D.; Ferry, R.J.; Niemann, R.C.; Roop, B.

    1991-01-01

    The Advanced Photon Source (APS) Storage Ring Vacuum Chambers (SRVC) are constructed of aluminum. The chamber design incorporates aluminum alloy 2219-T87 Conflat flanges welded to an aluminum alloy 6063-T5 extruded chamber body. Vacuum connections to the aluminum Conflat chamber flanges are by means of 304 stainless steel Conflat flanges. To evaluate the Conflat seal assemblies relative to vacuum bake cycles, a Conflat Bake Test Assembly (CBTA) was constructed, and thermal cycling tests were performed between room temperature and 150{degrees}C on both stainless steel to aluminum Conflat assemblies and aluminum to aluminum Conflat assemblies. A Helicoflex Bake Test Assembly (HBTA) was similarly constructed to evaluate Helicoflex seals. Both Conflat and Helicoflex seals were studied in a SRVC Sector String Test arrangement of five SRVC sections. The CBTA, HBTA and SRVC tests and their results are reported. 3 refs., 2 figs., 2 tabs.

  6. Ghostly Ring

    NASA Technical Reports Server (NTRS)

    2008-01-01

    [figure removed for brevity, see original site] Click on image for poster version

    This image shows a ghostly ring extending seven light-years across around the corpse of a massive star. The collapsed star, called a magnetar, is located at the exact center of this image. NASA's Spitzer Space Telescope imaged the mysterious ring around magnetar SGR 1900+14 in infrared light. The magnetar itself is not visible in this image, as it has not been detected at infrared wavelengths (it has been seen in X-ray light).

    Magnetars are formed when a massive giant star ends its life in a supernova explosion, leaving behind a super dense neutron star with an incredibly strong magnetic field. The ring seen by Spitzer could not have formed during the original explosion, as any material as close to the star as the ring would have been disrupted by the supernova shock wave. Scientists suspect that the ring my actually be the edges of a bubble that was hollowed out by an explosive burst from the magnetar in 1998. The very bright region near the center of the image is a cluster of young stars, which may be illuminating the inner edge of the bubble, making it look like a ring in projection.

    This composite image was taken using all three of Spitzer's science instruments. The blue color represents 8-micron infrared light taken by the infrared array camera, green is 16-micron light from the infrared spectograph, and red is 24-micron radiation from the multiband imaging photometer.

  7. Luminescent Rings

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This view shows the unlit face of Saturn's rings, visible via scattered and transmitted light. In these views, dark regions represent gaps and areas of higher particle densities, while brighter regions are filled with less dense concentrations of ring particles.

    The dim right side of the image contains nearly the entire C ring. The brighter region in the middle is the inner B ring, while the darkest part represents the dense outer B Ring. The Cassini Division and the innermost part of the A ring are at the upper-left.

    Saturn's shadow carves a dark triangle out of the lower right corner of this image.

    The image was taken in visible light with the Cassini spacecraft wide-angle camera on June 8, 2005, at a distance of approximately 433,000 kilometers (269,000 miles) from Saturn. The image scale is 22 kilometers (14 miles) per pixel.

    The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

    For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

  8. Cave Rings

    DTIC Science & Technology

    2010-10-13

    hypothesis, that cave rings are formed in the same manner as coffee rings[3], that is, due to the enhanced deposition at the edges of sessile drops ...Literature The ‘splash ring’ conjecture is described in [5]. It is claimed that 45◦ is the most probable angle for secondary drops to be ejected at, and that...ring’ is the deposit formed when a sessile drop of a solution containing dissolved particles, such as coffee or salt, dries. This was investigated by

  9. The orbits of the uranian satellites and rings, the gravity field of the uranian system, and the orientation of the pole of Uranus

    SciTech Connect

    Jacobson, R. A.

    2014-11-01

    French et al. determined the orbits of the Uranian rings, the orientation of the pole of Uranus, and the gravity harmonics of Uranus from Earth-based and Voyager ring occultations. Jacobson et al. determined the orbits of the Uranian satellites and the masses of Uranus and its satellites from Earth-based astrometry and observations acquired with the Voyager 2 spacecraft; they used the gravity harmonics and pole from French et al. Jacobson and Rush reconstructed the Voyager 2 trajectory and redetermined the Uranian system gravity parameters, satellite orbits, and ring orbits in a combined analysis of the data used previously augmented with additional Earth-based astrometry. Here we report on an extension of that work that incorporates additional astrometry and ring occultations together with improved data processing techniques.

  10. Cyclopropane-ring formation in the acyl groups of chlorosome glycolipids is crucial for acid resistance of green bacterial antenna systems.

    PubMed

    Mizoguchi, Tadashi; Tsukatani, Yusuke; Harada, Jiro; Takasaki, Shin; Yoshitomi, Taichi; Tamiaki, Hitoshi

    2013-07-01

    Green photosynthetic bacteria have unique light-harvesting antenna systems called chlorosomes. Chlorobaculum tepidum, a model organism of the bacteria, biosynthesized monogalactosyl- and rhamnosylgalactosyldiacylglycerides possessing a methylene-bridged palmitoleyl group characterized by a cis-substituted cyclopropane ring as the dominant glycolipids of its chlorosome surface. The formation of the cyclopropane ring was chemically inhibited by supplementation of sinefungin, an analog of S-adenosyl-L-methionine, into the bacterial cultivation. The presence of the cyclopropane ring reinforced acid resistance of the light-harvesting chlorosomes and suppressed acidic demetalation (pheophytinization) of bacteriochlorophyll-c pigments constructing the core part of chlorosomes. The ring-formation would represent direct and post-synthetic modifications of chlorosome membrane properties and was tolerant of acidic environments.

  11. In-situ calibration: migrating control system IP module calibration from the bench to the storage ring

    SciTech Connect

    Weber, Jonah M.; Chin, Michael

    2002-04-30

    The Control System for the Advanced Light Source (ALS) at Lawrence Berkeley National Lab (LBNL) uses in-house designed IndustryPack(registered trademark) (IP) modules contained in compact PCI (cPCI) crates with 16-bit analog I/O to control instrumentation. To make the IP modules interchangeable, each module is calibrated for gain and offset compensation. We initially developed a method of verifying and calibrating the IP modules in a lab bench test environment using a PC with LabVIEW. The subsequent discovery that the ADCs have significant drift characteristics over periods of days of installed operation prompted development of an ''in-situ'' calibration process--one in which the IP modules can be calibrated without removing them from the cPCI crates in the storage ring. This paper discusses the original LabVIEW PC calibration and the migration to the proposed in-situ EPICS control system calibration.

  12. Saturn's ``Gossamer'' Ring: The F Ring's Inner Sheet

    NASA Astrophysics Data System (ADS)

    Showalter, M. R.; Burns, J. A.; Hamilton, D. P.

    1998-09-01

    Recent Galileo and Earth-based images have revealed for the first time that Jupiter's ``gossamer'' ring is actually composed of two rings, one bounded at the outer edge by Amalthea and the other bounded by Thebe. Dynamical models suggest that these rings are composed of dust grains ejected off the surfaces of the two moons, which then evolve inward under Poynting-Robertson drag. A very faint sheet of material filling the region between Saturn's A and F Rings reported by Burns et al. (BAAS 15, 1013--1014, 1983) may be a dynamically analogous system, in which dust escapes from the F Ring and evolves inward to the A Ring. Unlike Jupiter's gossamer rings, however, the inner sheet of Saturn's F Ring has been well observed from a large range of phase angles and visual wavelengths by Voyager. Voyager images reveal that this faint ring shows a tenfold increase in brightness between phase angles of 125(deg) and 165(deg) , indicating that it is composed of fine dust microns in size. Preliminary estimates of the normal optical depth fall in the range 1--2*E(-4) , depending on the dust size distribution assumed. Initial spectrophotometry reveals that the ring is neutral in color. The ring is uniform in brightness over the entire region between the two rings, with no evidence for internal structure associated with Prometheus and Atlas, suggesting that neither of these embedded moons acts as either a source or a sink. We will refine the aforementioned measurements and develop photometric models to better constrain the properties of the dust in this ring. This will enable us to relate the dust population to that in the F Ring proper, and to better explore the dynamical processes at work.

  13. Investigation of factors affecting loosening of Ilizarov ring-wire external fixator systems at the bone-wire interface.

    PubMed

    Donaldson, Finn E; Pankaj, Pankaj; Simpson, A Hamish R W

    2012-05-01

    The potential for peri-implant bone yielding and subsequent loosening of Ilizarov ring-wire external fixation systems was investigated using non-linear finite element (FE) analyses. A strain-based plasticity model was employed to simulate bone yielding. FE models also incorporated contact behavior at the wire-bone interface, orthotropic elasticity, and periosteal-endosteal variation of bone properties. These simulations were used to determine the extent and location of yielding with change in age-related bone structure and properties for the bone-Ilizarov construct at the tibial midshaft. At critical wire-bone interfaces, the predicted volume of yielded bone with four wires (on either side of the fracture) was ∼40% of that with two wires. Old-aged cases showed considerably greater bone yielding at the wire-bone interface than young cases (1.7-2.2 times greater volumes of yielded bone). The volume of yielded bone at all wire-bone interfaces decreased with an increase in wire pre-tension. The absence of continuous through-thickness yielding offers an explanation for the clinical observation that Ilizarov ring-wire fixation can provide stable fracture fixation even in bone with high porosity.

  14. Understanding the Dynamics of the Coupled Ring Current Radiation Belt System Using 4D VERB Simulations

    NASA Astrophysics Data System (ADS)

    Shprits, Y.; Kellerman, A. C.; Drozdov, A.; Orlova, K.; Spasojevic, M.

    2014-12-01

    Predicting and understanding the non-linear response of different electron populations in the inner magnetosphere, including ring current and higher energy radiation belts, has been a grand challenge since the beginning of the space age. During this past decade, there have been a number of long-term simulations that used lower energy boundary condition observations around geosynchronous orbit. In this study, we set up observations at around 15 RE and study how the combined convective-diffusive transport can result in the acceleration of keV to relativistic and ultra-relativistic energies. We show that while lower energy radial transport is dominated by the convection, higher energy transport is dominated by the diffusive radial transport. MLT dependent diffusion confidents allow us to study how difference in wave properties at different MLT can influence the dynamics of the particles. Inclusion of adiabatic changes also allows us to study the radial transport that results from pitch-angle scattering and adiabatic changes. We also show that there exists an intermediate range of energies for electrons for which both processes work simultaneously. We show the comparison of the 4D VERB simulations with the Van Allen Probes measurements.

  15. Study of photon–magnon coupling in a YIG-film split-ring resonant system

    SciTech Connect

    Bhoi, B.; Aiyar, R.; Cliff, T.; Maksymov, I. S.; Kostylev, M.; Venkataramani, N.; Prasad, S.; Stamps, R. L.

    2014-12-28

    By using the stripline Microwave Vector–Network Analyser Ferromagnetic Resonance and Time Domain spectroscopy techniques, we study a strong coupling regime of magnons to microwave photons in the planar geometry of a lithographically formed split-ring resonator (SRR) loaded by a single-crystal epitaxial yttrium–iron–garnet (YIG) film. Strong anti-crossing of the photon modes of SRR and of the magnon modes of the YIG film is observed in the applied-magnetic-field resolved measurements. The coupling strength extracted from the experimental data reaches 9% at 3 GHz. Theoretically, we propose an equivalent circuit model of the SRR loaded by a magnetic film. This model follows from the results of our numerical simulations of the microwave field structure of the SRR and of the magnetisation dynamics in the YIG film driven by the microwave currents in the SRR. The results obtained with the equivalent-circuit model are in good agreement with the experiment. This model provides a simple physical explanation of the process of mode anti-crossing. Our findings are important for future applications in microwave quantum photonic devices as well as in nonlinear and magnetically tuneable metamaterials exploiting the strong coupling of magnons to microwave photons.

  16. Effects of pressure anisotropy on magnetospheric magnetohydrodynamics equilibrium of an internal ring current system

    SciTech Connect

    Furukawa, M.

    2014-01-15

    Effects of pressure anisotropy on magnetospheric magnetohydrodynamics equilibrium are studied analytically and numerically, where the plasma is confined by only poloidal magnetic field generated by an internal ring current. The plasma current due to finite pressure can be divided into two components; one remains at isotropic pressure and the other arises from pressure anisotropy. When p{sub ⊥}, the pressure perpendicular to the magnetic field, is larger than p{sub ∥}, the pressure parallel to the magnetic field, those two components of plasma current tend to cancel each other to reduce the total amount of plasma current. Equilibrium beta limit is also examined, where the beta is a ratio of the plasma pressure to the magnetic pressure. The equilibrium beta limit decreases as the pressure anisotropy becomes strong. The beta value is strictly limited by ellipticity of the equilibrium equation when p{sub ∥}>p{sub ⊥}. On the other hand, when p{sub ⊥}>p{sub ∥}, although the tendency of the beta limit agrees with the ellipticity condition of the equilibrium equation, equilibria with a hyperbolic region can be obtained by iterative procedure with practically reasonable convergence criteria.

  17. A Search for Rings, Moons, or Debris in the Pluto System during the 2006 July 12 Occultation

    NASA Astrophysics Data System (ADS)

    Pasachoff, Jay M.; Babcock, B. A.; Souza, S. P.; Gangestad, J. W.; Jaskot, A. E.; Elliot, J. L.; Gulbis, A. A.; Person, M. J.; Kramer, E. A.; Adams, E. R.; Zuluaga, C. A.; Pike, R. E.; Francis, P. J.; Lucas, R.; Bosh, A. S.; Ramm, D. J.; Greenhill, J. G.; Giles, A. B.; Dieters, S. W.

    2006-09-01

    We examined our data runs from four sites for the 2006 July 12 occultation of the star P384.2 (McDonald & Elliot, AJ 120, 1599, 2000; UCAC2 26039859), to search for moons, rings, or other debris in the Pluto system. Our data runs extended 80 minutes, or 115,200 km. Motivated by the discovery of P1 (Hydra) and P2 (Nix), each approximately 50 km in diameter and thought to result from the same collision that formed Charon, S. A. Stern et al. (Nature 439, 946-948, 2006) suggested that such matter might be detectable. Though their first estimate was unobservably low at 5×10-6, it could change by a factor of 10,000 or more in either direction (Stern, private communication). Our cloudless data sets, in declining order of S/N, used our Portable Occultation, Eclipse, and Transit Systems (POETS; Souza et al., in preparation) and include those from the 2.3-m ANU telescope at Siding Spring, Australia; 0.8-m Black Springs telescope near Adelaide, and the 1.8-m EOS telescope at Mt. Stromlo; though the atmospheric observation time at the 1-m Mt. Canopus Telescope at Hobart could be recovered from the comparison stars, cloudy intervals prevent full recovery during the ring/debris possible interval. Our observing with the 1-m Mt. John University Observatory in New Zealand was rendered impossible by the lack of electricity resulting from a major snowstorm. For the ring/debris search, we also evaluated data from past Pluto (Pasachoff et al., AJ 129, 1718-1723, 2005) and Charon (Gulbis et al., Nature 439, 48-51, 2006) occultations. See also Elliot et al. and Gulbis et al. (this meeting). We thank Ian Ritchie of Electro Optic Systems (Mt. Stromlo Observatory), Ian Bedford, Lyndon Hemer, and Fraser Farrell (Black Springs Observatory), and Blair Lade (Stockport Observatory). This work was partially supported by NASA Planetary Astronomy Grants NNH04ZSS001N, NNG04GE48G, and NNG04GF25G.

  18. Cooperative activation of cyclobutanones and olefins leads to bridged ring systems by a catalytic [4 + 2] coupling

    NASA Astrophysics Data System (ADS)

    Ko, Haye Min; Dong, Guangbin

    2014-08-01

    Bridged ring systems are widely found in natural products, and successful syntheses of them frequently feature intramolecular Diels-Alder reactions. These reactions are subclassified as either type I or type II depending on how the diene motif is tethered to the rest of the substrate (type I are tethered at the 1-position of the diene and type II at the 2-position). Although the type I reaction has been used with great success, the molecular scaffolds accessible by the type II reactions are limited by the strain inherent in the formation of an sp2 carbon at a bridgehead position. Here, we describe a complementary approach that provides access to these structures through the C-C activation of cyclobutanones and their coupling with olefins. Various alkenes have been coupled with cyclobutanones to provide a range of bridged skeletons. The ketone group of the products serves as a convenient handle for downstream functionalization.

  19. Flexure-Ring for Centering a Concave Lens in a Bore of a Housing for an Optical System

    NASA Technical Reports Server (NTRS)

    Ford, Virginia G. (Inventor)

    2002-01-01

    A flexure-ring is provided for centering a lens in a bore of a housing with 3N lens contacting stubs, where N is an integer equal to or greater than one. The stubs are formed by increasing the inside diameter of the ring made to fit tightly around a lens except at 3N locations for the aforesaid stubs, and said ring having an outside diameter made to fit tightly inside the housing bore locations. Behind each stub, a segment of the ring is removed down to a chord perpendicular to a ring diameter passing through the center of each stub. That chord is selected to have a length greater than the lens contacting surface of the stub, thereby to produce a reduced cross section of the ring on both sides of the stub to serve as flexures in relieving stresses due to different coefficients of thermal expansion of the three parts involved due to changes in temperature while in use.

  20. Removal of copper and iron by polyurethane foam column in FIA system for the determination of nickel in pierced ring.

    PubMed

    Vongboot, Monnapat; Suesoonthon, Monrudee

    2015-01-01

    Polyurethane foam (PUF) mini-column was used to eliminate copper and iron for the determination of nickel in pierced rings. The PUF mini-column was connected to FIA system for on-line sorption of copper and iron in complexes form of CuSCN(+) and FeSCN(2+). For this season, the acid solution containing a mixture of Ni(II), Fe(III), Cu(II) and SCN(-) ions was firstly flew into the PUF column. Then, the percolated solution which Fe(III) and Cu(II) ions is separated from analysis was injected into FIA system to react with 4-(2-pyridylazo) resorcinol (PAR) reagent in basic condition which this method is called pH gradient technique. The Ni-PAR complexes obtained were measured theirs absorbance at 500 nm by UV visible spectrophotometer. In this study, it was found that Cu(II) and Fe(III) were completely to form complexes with 400 mmol/L KSCN and entirely to eliminate in acidic condition at pH 3.0. In the optimum condition of these experiments, the method provided the linear relationship between absorbance and the concentration of Ni(II) in the range from 5.00 to 30.00 mg/L. Linear equation is y=0.0134x+0.0033 (R(2)=0.9948). Precision, assessed in the term of the relative standard deviation, RSD, and accuracy for multiple determinations obtained in values of 0.77-1.73% and 97.4%, respectively. The level of an average amount of Ni(II) in six piercing rings was evaluated to be 14.78 mg/g.

  1. Design of a three-axis magnetic field measurement system for the magnetic shield of the ring laser gyroscope

    NASA Astrophysics Data System (ADS)

    Rong, Chuiyu; Yao, Xu

    2015-10-01

    The magnetic field is one of the main causes of zero drift in a Ring Laser Gyroscope (RLG), which should be avoided by adopting a magnetic shielding system. The Gauss Meter is usually used to measure the magnetic shielding effectiveness. Generally, the traditional Gauss Meter has advantages of high measure range and high reliability, however, its drawbacks such as complex structure, high price and the PC client software cannot be customized at will, are also obvious. In this paper, aiming at a type of experimental magnetic shielding box of RLG, we design a new portable three-axis magnetic field measurement system. This system has both high modularity degree and reliability, with measuring range at ±48Gs, max resolution at 1.5mGs and can measure the magnetic field in x, y and z direction simultaneously. Besides, its PC client software can be easily customized to achieve the automatic DAQ, analysis, plotting and storage functions. The experiment shows that, this system can meet the measuring requirements of certain type of experimental magnetic shielding box for RLG, meanwhile, for the measurement of some other magnetic shielding effectiveness, this system is also applicable.

  2. Synthetic approaches to the bicyclo[2.2.2]diazaoctane ring system common to the paraherquamides, stephacidins and related prenylated indole alkaloids.

    PubMed

    Miller, Kenneth A; Williams, Robert M

    2009-11-01

    The bicyclo[2.2.2]diazaoctane ring system is common to a number of highly biologically active secondary metabolites isolated from numerous species of fungi. In this tutorial review, we describe the varied synthetic approaches that have been employed to construct this ring system in the course of recent total synthesis endeavors, and this review should be of interest to synthetic organic chemists and natural product chemists. Detailed herein are a number of synthetic disconnections including intramolecular S(N)2' cyclizations, biomimetic Diels-Alder reactions, radical cyclizations, and cationic cascade reactions.

  3. Uranus' Rings: Leading up to RPX

    NASA Astrophysics Data System (ADS)

    de Pater, I.; Showalter, M.; Hammel, H.; Gibbard, S.; Lissauer, J.

    We summarize recent HST and Keck observations of the uranian ring system, taken over the past years while the viewing geometry is changing. Some highlights of our campaign to date include: i) Detection of a ring system outside of Uranus main ring system by HST (Showalter and Lissauer, Science 311, p.973, 2006), followed by color information from Keck (de Pater et al, Science 312, p.92, 2006). This system consists of two rings. The inner ring, U2, is red and relatively narrow like Saturn's G ring, while the outer ring, U1, is much broader in extent and very blue, like Saturn's E ring. Just like Enceladus is located within the E ring, moon Mab is inside U1. Saturn's E ring is most likely produced by geyser activity on Enceladus. Mab, being over 20 times smaller, is unlikely to be geologically active. However, being this small, its size is optimal to produce a ring via meteorite sputtering. ii) Detection of a ring interior to the main ring system, which might be ring 1986U2R, discovered by Voyager, though its extent and location is different from the Voyager ring. iii) Dust sheets in between the main ring. These may be similar to the dust sheets seen by Voyager in forward scattered light, yet our observations indicate large changes from the Voyager era iv) New moons were detected by HST. The orbits of some of these moons appear to be somewhat erratic. The color of moon Mab appears to be more similar to that of the large outer moons than the small inner moons. Earth will cross Uranus' ring plane three times in 2007-2008 (2 May, 16 Aug. 2007, 20 Feb. 2008), and the Sun will cross it once (7 Dec. 2007). At these times optically thin dusty rings will brighten considerably, making this period an ideal time to study Uranus' outer ring system. Between the May and August crossings, as well as between December and February, the Earth and Sun are on opposite sides of the rings, so that any optically thick rings will essentially be invisible. This allows phenomena normally

  4. Metallic Ca-Rh/C-methanol, a high-performing system for the hydrodechlorination/ring reduction of mono- and poly chlorinated aromatic substrates.

    PubMed

    Mitoma, Yoshiharu; Kakeda, Mitsunori; Simion, Alina Marieta; Egashira, Naoyoshi; Simion, Cristian

    2009-08-01

    We investigated the reduction of some substituted mono- and poly chlorobenzenes bearing functional groups such as methyl, methoxy, hydroxyl, and amino, under mild conditions (80 degrees C and magnetic stirring, for 2 h) using a system consisting of metallic calcium and methanol (as hydrogen donor system) and 5% wt. Rh/C (as hydrodechlorination/ring reduction catalyst). Hydrodechlorination easily took place for methoxy- and alkyl-chlorobenzenes, yielding the corresponding hydrodechlorinated compounds (57-76%) and affording as secondary reaction products the ring-reduced compounds (16-43%). Treatment of hydroxy- and amino-chlorobenzenes under the same conditions, respectively, gave corresponding hydrodechlorinated compounds (over 60%) along with the ring-reduced compounds. Results show that the reaction of substituted polychlorinated benzenes needs a longer reaction time (6 h), the transformation being nevertheless complete.

  5. Cavity ring-down spectroscopy with an automated control feedback system for investigating nitrate radical surface chemistry reactions

    PubMed Central

    Flemmer, Michael M.; Ham, Jason E.

    2015-01-01

    Nitrate radical (NO3•) surface chemistry of indoor environments has not been well studied due to the difficulty in generating and maintaining NO3• at low concentrations for long term exposures. This article presents the Surface Chemistry Reactant Air Delivery and Experiment System (SCRADES), a novel feedback controlled system developed to deliver nitrate radicals at specified concentrations (50–500 ppt, ±30 ppt) and flow rates (500–2000 ml min−1) to a variety of indoor surfaces to initiate reaction chemistry for periods of up to 72 h. The system uses a cavity ring-down spectrometer (CRDS), with a detection limit of 1.7 ppt, to measure the concentration of NO3• supplied to a 24 l experiment chamber. Nitrate radicals are introduced via thermal decomposition of N2O5 and diluted with clean dry air until the desired concentration is achieved. Additionally, this article addresses details concerning NO3• loss through the system, consistency of the NO3• concentration delivered, and stability of the CRDS cavity over long exposure durations (72 h). PMID:22938328

  6. Kayser-Fleischer Rings

    MedlinePlus

    ... to know about Wilson Disease Kayser-Fleischer Rings Definition Kayser-Fleischer Ring: Clinical sign. Brownish-yellow ring ... Diet & Nutrition Kayser-Fleischer Rings Wilson Disease FAQs Definitions Transplantation For Patients & Families Resources Membership Events Centers ...

  7. Implementing Digital Feedback Controls for the Multiple Simultaneous Ring Cavities in the FASOR-X System

    DTIC Science & Technology

    2011-09-01

    choices for gains and detector saturation and trip levels critically important. For example, some absorption within the LBO crystal or its heated...the chiller ; 2) activate the SFG heater; 3) turn on the Main System Software via a single click and wait 10-20 minutes for the system to produce

  8. How Jupiter's Ring Was Discovered.

    ERIC Educational Resources Information Center

    Elliot, James; Kerr, Richard

    1985-01-01

    "Rings" (by astronomer James Elliot and science writer Richard Kerr) is a nontechnical book about the discovery and exploration of ring systems from the time of Galileo to the era of the Voyager spacecraft. One of this book's chapters is presented. (JN)

  9. A microcomputer-based data acquisition and control system for the direct shear, ring shear, triaxial shear, and consolidation tests

    USGS Publications Warehouse

    Powers, Philip S.

    1983-01-01

    This report is intended to provide internal documentation for the U.S. Geological Survey laboratory's automatic data acquisition system. The operating procedures for each type of test are designed to independently lead a first-time user through the various stages of using the computer to control the test. Continuing advances in computer technology and the availability of desktop microcomputers with a wide variety of peripheral equipment at a reasonable cost can create an efficient automated geotechnical testing environment. A geotechnical testing environment is shown in figure 1. Using an automatic data acquisition system, laboratory test data from a variety of sensors can be collected, and manually or automatically recorded on a magnetic device at the same apparent time. The responses of a test can be displayed graphically on a CRT in a matter of seconds, giving the investigator an opportunity to evaluate the test data, and to make timely, informed decisions on such matters as whether to continue testing, abandon a test, or modify procedures. Data can be retrieved and results reported in tabular form, or graphic plots, suitable for publication. Thermistors, thermocouples, load cells, pressure transducers, and linear variable differential transformers are typical sensors which are incorporated in automated systems. The geotechnical tests which are most practical to automate are the long-term tests which often require readings to be recorded outside normal work hours and on weekends. Automation applications include incremental load consolidation tests, constant-rate-of-strain consolidation tests, direct shear tests, ring shear tests, and triaxial shear tests.

  10. The fascinating construction of pyridine ring systems by transition metal-catalysed [2 + 2 + 2] cycloaddition reactions.

    PubMed

    Heller, Barbara; Hapke, Marko

    2007-07-01

    Cycloaddition reactions compose one of the most important classes of reactions when it comes to the simultaneous formation of several bonds in one reaction step. The de novo construction of carbocyclic aromatic systems from acetylenes was also found as an excellent possibility for the assembly of heteroaromatic systems. The transition metal-catalysed [2 + 2 + 2] cycloaddition reaction constitutes a fascinating tool for the synthesis of pyridines from nitriles and the most recent developments demonstrate the ability to control the substitution pattern as well as the possibility of introducing chirality by the use of achiral substrates and a chiral catalyst under mild conditions. In this tutorial review we are focusing on the de novo construction of pyridine ring systems by the transition metal-catalysed [2 + 2 + 2] cycloaddition reaction. After surveying the mechanistic features and intermediates of the reaction depending on the different metal complexes used, we depict the preparation of achiral pyridine derivatives. The last section describes the advances in the synthesis of chiral pyridines and biaryls using the cyclotrimerization method. The various possibilities of introducing chirality by catalytic means are presented and illustrated by instructive examples. This review will be of interest for people active in: Organic Chemistry, Organometallic Chemistry, Transition Metal Chemistry, Stereoselective Synthesis, Heterocyclic Chemistry.

  11. Castro ring zone: a 4,500-km2 fossil hydrothermal system in the Challis volcanic field, central Idaho.

    USGS Publications Warehouse

    Criss, R.E.; Ekren, E.B.; Hardyman, R.F.

    1984-01-01

    The largest fossil hydrothermal system occupying a 4500 km2 area in central Idaho is revealed by delta 18O studies. The remains of this meteoric-hydrothermal system are preserved within a sharply bounded, 15 km wide, 70-km-diameter annulus of low delta 18O rock (+2.0 to -8.8per mille) termed the Castro ring zone. The zone is centred on a less depleted (+4.5) core zone consisting of granitic rocks of the Castro pluton. This 700-km2 Eocene subvolcanic batholith has intruded, domed, and hydrothermally metamorphosed a thick sequence of Challis Volcanics, the stratigraphically low rocks in the 2000-km2 Van Horn Peak and the 1000-km2 Thunder Mountain cauldron complexes being most strongly altered. Less extreme 18O depletions occur in the youngest major ash-flow sheets of these complexes, indicating a vertical 18O gradient. Water/rock ratios of geothermal systems are surprisingly insensitive to the circulation scale.-L.-di H.

  12. The LEO Archipelago: A system of earth-rings for communications, mass-transport to space, solar power, and control of global warming

    NASA Astrophysics Data System (ADS)

    Meulenberg, Andrew; Karthik Balaji, P. S.

    2011-06-01

    Man's quest to get into space is hindered by major problems (e.g., system-development and capital costs, expense of putting mass into orbit, trapped-radiation belts, and environmental impact of a large increase in rocket launches). A multi-purpose low-earth-orbit system of rings circling the earth - the "LEO ARCHIPELAGO TM" - is proposed as a means of solving or bypassing many of them. A fiber-optic ring about the earth would be an initial testing and developmental stage for the Ring Systems, while providing cash-flow through a LEO-based, high-band-width, world-wide communication system. A low-earth-orbit-based space-elevator system, "Sling-on-a-Ring TM", is proposed as the crucial developmental stage of the LEO Archipelago. Being a LEO-based heavy-mass lifter, rather than earth- or GEO-based, it is much less massive and therefore less costly than other proposed space-elevators. With the advent of lower-cost, higher-mass transport to orbit, the options for further space development (e.g., space solar power, radiation, and space-debris dampers, sun shades, and permanent LEO habitation) are greatly expanded. This paper provides an update of the Sling-on-a-Ring concept in terms of new materials, potential applications, and trade-offs associated with an earlier model. The impact of Colossal Carbon Tubes, CCT, a new material with high tensile strength, extremely-low density, and other favorable properties, and other new technologies (e.g., solar-powered lasers, power beaming to near-space and earth, and thermal-control systems) on the development of associated LEO-Ring systems is also explored. The material's effect on the timeline for the system development indicates the feasibility of near-term implementation of the system (possibly within the decade). The Sling-on-a-Ring can provide a less-expensive, environment-friendly mode of access to space. This would pave the way (via eventual operation at >1000 t per day by 2050) for large scale development of space

  13. Ringing wormholes

    SciTech Connect

    Konoplya, R.A.; Molina, C.

    2005-06-15

    We investigate the response of traversable wormholes to external perturbations through finding their characteristic frequencies and time-domain profiles. The considered solution describes traversable wormholes between the branes in the two brane Randall-Sundrum model and was previously found within Einstein gravity with a conformally coupled scalar field. The evolution of perturbations of a wormhole is similar to that of a black hole and represents damped oscillations (ringing) at intermediately late times, which are suppressed by power-law tails (proportional to t{sup -2} for monopole perturbations) at asymptotically late times.

  14. Rings from Close Encounters

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-09-01

    Weve recently discovered narrow sets of rings around two minor planets orbiting in our solar system. How did these rings form? A new study shows that they could be a result of close encounters between the minor planets and giants like Jupiter or Neptune.Unexpected Ring SystemsPositions of the centaurs in our solar system (green). Giant planets (red), Jupiter trojans (grey), scattered disk objects (tan) and Kuiper belt objects (blue) are also shown. [WilyD]Centaurs are minor planets in our solar system that orbit between Jupiter and Neptune. These bodies of which there are roughly 44,000 with diameters larger than 1 km have dynamically unstable orbits that cross paths with those of one or more giant planets.Recent occultation observations of two centaurs, 10199 Chariklo and 2060 Chiron, revealed that these bodies both host narrow ring systems. Besides our four giant planets, Chariklo and Chiron are the only other bodies in the solar system known to have rings. But how did these rings form?Scientists have proposed several models, implicating collisions, disruption of a primordial satellite, or dusty outgassing. But a team of scientists led by Ryuki Hyodo (Paris Institute of Earth Physics, Kobe University) has recently proposed an alternative scenario: what if the rings were formed from partial disruption of the centaur itself, after it crossed just a little too close to a giant planet?Tidal Forces from a GiantHyodo and collaborators first used past studies of centaur orbits to estimate that roughly 10% of centaurs experience close encounters (passing within a distance of ~2x the planetary radius) with a giant planet during their million-year lifetime. The team then performed a series of simulations of close encounters between a giant planet and a differentiated centaur a body in which the rocky material has sunk to form a dense silicate core, surrounded by an icy mantle.Some snapshots of simulation outcomes (click for a closer look!) for different initial states of

  15. Physics of planetary rings

    NASA Astrophysics Data System (ADS)

    Gorkavyi, N.

    2007-08-01

    It is difficult to enumerate all the surprises presented by the planetary rings. The Saturnian rings are stratified into thousands of ringlets and the Uranian rings are compressed into narrow streams, which for some reason or other differ from circular orbits like the wheel of an old bicycle. The edge of the rings is jagged and the rings themselves are pegged down under the gravitational pressure of the satellites, bending like a ship's wake. There are spiral waves, elliptical rings, strange interlacing of narrow ringlets, and to cap it all one has observed in the Neptunian ring system three dense, bright arcs - like bunches of sausages on a transparent string. For celestial mechanics this is a spectacle as unnatural as a bear's tooth in the necklace of the English queen. In the dynamics of planetary rings the physics of collective interaction was supplemented by taking collisions between particles into account. One was led to study a kinetic equation with a rather complex collision integral - because the collisions are inelastic - which later on made it possible, both by using the Chapman-Enskog method and by using the solution of the kinetic equation for a plasma in a magnetic field, to reduce it to a closed set of (hydrodynamical) moment equations [1]. The hydrodynamical instabilities lead to the growth of short-wavelength waves and large-scale structures of the Saturnian rings [1]. We have shown that the formation of the existing dense Uranian rings is connected with the capture of positively drifting ring particles in inner Lindblad resonances which arrest this drift [1]. After the formation of dense rings at the positions of satellite resonances the collective interaction between resonant particles is amplified and the rings can leave the resonance and drift away from the planet and the parent resonance. We can expect in the C ring an appreciable positive ballistic particle drift caused by the erosion of the B ring by micrometeorites. It is therefore natural

  16. Dual inhibition of HCV and HIV by ring-expanded nucleosides containing the 5:7-fused imidazo[4,5-e][1,3]diazepine ring System. In vitro results and implications

    PubMed Central

    Zhang, Ning; Zhang, Peng; Baier, Andrea; Cova, Lucyna; Hosmane, Ramachandra S.

    2014-01-01

    Examples of ring-expanded nucleosides (RENs), represented by general structures 1 and 2, exhibited dual anti-HCV and anti-HIV activities in both cell culture systems and the respective target enzyme assays, including HCV NTPase/helicase and human RNA helicase DDX3. Since HCV is a leading co-infection in late stage HIV AIDS patients, often leading to liver cirrhosis and death, the observed dual inhibition of HCV and HIV by the target nucleoside analogues has potentially beneficial implications in treating HIV patients infected with HCV. PMID:24461293

  17. High numerical aperture ring field projection system for extreme ultraviolet lithography

    DOEpatents

    Hudyma, Russell; Shafer, David

    2001-01-01

    An all-reflective optical system for a projection photolithography camera has a source of EUV radiation, a wafer and a mask to be imaged on the wafer. The optical system includes a first convex mirror, a second mirror, a third convex mirror, a fourth concave mirror, a fifth convex mirror and a sixth concave mirror. The system is configured such that five of the six mirrors receives a chief ray at an incidence angle of less than substantially 9.degree., and each of the six mirrors receives a chief ray at an incidence angle of less than substantially 14.degree.. Four of the six reflecting surfaces have an aspheric departure of less than substantially 12 .mu.m. Five of the six reflecting surfaces have an aspheric departure of less than substantially 12 .mu.m. Each of the six reflecting surfaces has an aspheric departure of less than substantially 16 .mu.m.

  18. High numerical aperture ring field projection system for extreme ultraviolet lithography

    DOEpatents

    Hudyma, Russell; Shafer, David R.

    2001-01-01

    An all-reflective optical system for a projection photolithography camera has a source of EUV radiation, a wafer and a mask to be imaged on the wafer. The optical system includes a first convex mirror, a second mirror, a third convex mirror, a fourth concave mirror, a fifth convex mirror and a sixth concave mirror. The system is configured such that five of the six mirrors receive a chief ray at an incidence angle of less than substantially 9.degree., and each of the six mirrors receives a chief ray at an incidence angle of less than substantially 14.degree.. Four of the six reflecting surfaces have an aspheric departure of less than substantially 12 .mu.m. Five of the six reflecting surfaces have an aspheric departure of less than substantially 12 .mu.m. Each of the six reflecting surfaces has an aspheric departure of less than substantially 16 .mu.m.

  19. High numerical aperture ring field projection system for extreme ultraviolet lithography

    DOEpatents

    Hudyma, Russell

    2001-01-01

    An all-reflective optical system for a projection photolithography camera has a source of EUV radiation, a wafer and a mask to be imaged on the wafer. The optical system includes a first concave mirror, a second mirror, a third convex mirror, a fourth concave mirror, a fifth convex mirror and a sixth concave mirror. The system is configured such that five of the six mirrors receives a chief ray at an incidence angle of less than substantially 12.degree., and each of the six mirrors receives a chief ray at an incidence angle of less than substantially 15.degree.. Four of the six reflecting surfaces have an aspheric departure of less than substantially 7 .mu.m. Five of the six reflecting surfaces have an aspheric departure of less than substantially 14 .mu.m. Each of the six reflecting surfaces has an aspheric departure of less than 16.0 .mu.m.

  20. High numerical aperture ring field projection system for extreme ultraviolet lithography

    DOEpatents

    Hudyma, Russell

    2000-01-01

    An all-refelctive optical system for a projection photolithography camera has a source of EUV radiation, a wafer and a mask to be imaged on the wafer. The optical system includes a first concave mirror, a second mirror, a third convex mirror, a fourth concave mirror, a fifth convex mirror and a sixth concave mirror. The system is configured such that five of the six mirrors receives a chief ray at an incidence angle less than substantially 12.degree., and each of the six mirrors receives a chief ray at an incidence angle of less than substantially 15.degree.. Four of the six reflecting surfaces have an aspheric departure of less than substantially 7 .mu.m. Five of the six reflecting surfaces have an aspheric departure of less than substantially 14 .mu.m. Each of the six refelecting surfaces has an aspheric departure of less than 16.0 .mu.m.

  1. Structural, energetic, spectroscopic and QTAIM analyses of cation-π interactions involving mono- and bi-cyclic ring fused benzene systems.

    PubMed

    Hassan, Ayorinde; Dinadayalane, Tandabany C; Grabowski, Sławomir J; Leszczynski, Jerzy

    2013-12-28

    The effect of increasing the number of monocyclic six-membered rings or bicyclic rings of bicyclo[2.1.1]hexenyl fused to benzene on cation-π interactions involving alkali metal ions (Li(+), Na(+), and K(+)) has been investigated. The binding energy data at the B3LYP/6-311+G(2d,2p) level clearly indicate that the binding affinity of the metal ion with benzene is enhanced by increasing the number of rings fused irrespective of a monocyclic or a bicyclic ring. Calculated binding energies are in good agreement with the available experimental results. The binding strength of cations with ligands decreases in the order Li(+) > Na(+) > K(+). Our study establishes that trisannelation of bicyclo[2.1.1]hexene to benzene facilitates a very strong interaction between benzene and cations. Infrared (IR) frequencies and nuclear magnetic resonance (NMR) chemical shifts are shown to be valuable in characterizing cation-π interactions. The C-C bonds of the central six-membered rings are weakened due to metal ion binding. Based on the Quantum Theory of Atoms in Molecules (QTAIM), we have observed the presence of stabilizing H∙∙∙H interactions in two of the considered systems as opposed to the frequent description of these interactions as non-bonded repulsive interactions. Alkali metal ion binding with those two ligands slightly reduces the strength of such H∙∙∙H interactions.

  2. Total Synthesis and Evaluation of Vinblastine Analogues Containing Systematic Deep-Seated Modifications in the Vindoline Subunit Ring System: Core Redesign

    PubMed Central

    Schleicher, Kristin D.; Sasaki, Yoshikazu; Tam, Annie; Kato, Daisuke; Duncan, Katharine K.; Boger, Dale L.

    2013-01-01

    The total synthesis of a systematic series of vinblastine analogues that contain deep-seated structural modifications to the core ring system of the lower vindoline subunit is described. Complementary to the vindoline 6,5 DE ring system, compounds with 5,5, 6,6 and the reversed 5,6 membered DE ring systems were prepared. Both the natural cis and unnatural trans 6,6-membered ring systems proved accessible, with the latter representing a surprisingly effective class for analogue design. Following Fe(III)-promoted coupling with catharanthine and in situ oxidation to provide the corresponding vinblastine analogues, their evaluation provided unanticipated insights into how the structure of the vindoline subunit contributes to activity. Two potent analogues (81 and 44) possessing two different unprecedented modifications to the vindoline subunit core architecture were discovered that matched the potency of the comparison natural products and both lack the 6,7-double bond whose removal in vinblastine leads to a 100-fold drop in activity. PMID:23252481

  3. Enantioselective ring-opening reaction of meso-epoxides with ArSeH catalyzed by heterometallic Ti-Ga-Salen system.

    PubMed

    Yang, Minghua; Zhu, Chengjian; Yuan, Fang; Huang, Yijun; Pan, Yi

    2005-05-12

    The first example of enantioselective ring-opening reaction of meso-epoxides with aryl selenols to give optically active beta-arylseleno alcohol in up to 97% ee was realized, using a chiral Ti-Ga-Salen heterometallic catalyst. A strong synergistic effect of different Lewis acids in the system was exhibited in the catalytic process.

  4. Ground Movement in SSRL Ring

    SciTech Connect

    Sunikumar, Nikita; /UCLA /SLAC

    2011-08-25

    Users of the Stanford Synchrotron Radiation Lightsource (SSRL) are being affected by diurnal motion of the synchrotron's storage ring, which undergoes structural changes due to outdoor temperature fluctuations. In order to minimize the effects of diurnal temperature fluctuations, especially on the vertical motion of the ring floor, scientists at SSRL tried three approaches: painting the storage ring white, covering the asphalt in the middle of the ring with highly reflective Mylar and installing Mylar on a portion of the ring roof and walls. Vertical motion in the storage ring is measured by a Hydrostatic Leveling System (HLS), which calculates the relative height of water in a pipe that extends around the ring. The 24-hr amplitude of the floor motion was determined using spectral analysis of HLS data, and the ratio of this amplitude before and after each experiment was used to quantitatively determine the efficacy of each approach. The results of this analysis showed that the Mylar did not have any significant effect on floor motion, although the whitewash project did yield a reduction in overall HLS variation of 15 percent. However, further analysis showed that the reduction can largely be attributed to a few local changes rather than an overall reduction in floor motion around the ring. Future work will consist of identifying and selectively insulating these local regions in order to find the driving force behind diurnal floor motion in the storage ring.

  5. Mu-28: an open-framework fluorogallophosphate with a three-dimensional 12-membered ring channel system

    SciTech Connect

    Josien, Ludovic; Simon-Masseron, Angelique . E-mail: a.simon@univ-mulhouse.fr; Gramlich, Volker; Porcher, Florence; Patarin, Jogl

    2004-10-01

    A new three-dimensional (3-D) microporous fluorogallophosphate, named Mu-28, was obtained by hydrothermal synthesis. It was obtained in the presence of fluoride ions with 1,4-dimethylpiperazine as organic template. This new fluorogallophosphate, with chemical formula [Ga{sub 20}P{sub 20}O{sub 80}(OH){sub 6}F{sub 6}(H{sub 2}O){sub 4}(C{sub 6}H{sub 16}N{sub 2}){sub 6}] 8H{sub 2}O, crystallizes in the monoclinic system space group P2{sub 1} with the following unit cell parameters: a=13.23(1)A, b=15.40(1)A, c=14.80(1)A, {beta}=95.10(9){sup o} (Z=1, R1=0.0435 [I>2{sigma}(I)]). Its structure was determined by single-crystal X-ray diffraction with the help of {sup 31}P NMR spectroscopy. Mu-28 consists of a complex arrangement of GaO{sub 3}(OH,F)(H{sub 2}O){sub 2}, GaO{sub 4}(OH)F and GaO{sub 4}(OH){sub 2} octahedra, GaO{sub 4}F trigonal bipyramids and GaO{sub 3}(OH,F) and PO{sub 4} tetrahedra. It displays a 3-D channel system delimited by 12-membered ring openings.

  6. A free-flowing soap film combined with cavity ring-down spectroscopy as a detection system for liquid chromatography.

    PubMed

    Vogelsang, Markus; Welsch, Thomas; Jones, Harold

    2010-05-07

    We have shown that a free-flowing soap film has sufficiently high-quality optical properties to allow it to be used in the cavity of a ring-down spectrometer (CRDS). The flow rates required to maintain a stable soap film were similar to those used in liquid chromatography and thus allowed interfacing with an HPLC system for use as an optical detector. We have investigated the properties of the system in a relevant analytical application. The soap film/CRDS combination was used at 355 nm as a detector for the separation of a mixture of nitroarenes. These compounds play a role in the residue analysis of areas contaminated with explosives and their decomposition products. In spite of the short absorption path length (9 microm) obtained by the soap film, the high-sensitivity of CRDS allowed a limit of detection of 4 x 10(-6) in absorption units (AU) or less than 17 fmol in the detection volume to be achieved.

  7. Double-ring network model of the head-direction system

    NASA Astrophysics Data System (ADS)

    Xie, Xiaohui; Hahnloser, Richard H.; Seung, H. Sebastian

    2002-10-01

    In the head-direction system, the orientation of an animal's head in space is encoded internally by persistent activities of a pool of cells whose firing rates are tuned to the animal's directional heading. To maintain an accurate representation of the heading information when the animal moves, the system integrates horizontal angular head-velocity signals from the vestibular nuclei and updates the representation of directional heading. The integration is a difficult process, given that head velocities can vary over a large range and the neural system is highly nonlinear. Previous models of integration have relied on biologically unrealistic mechanisms, such as instantaneous changes in synaptic strength, or very fast synaptic dynamics. In this paper, we propose a different integration model with two populations of neurons, which performs integration based on the differential input of the vestibular nuclei to these two populations. We mathematically analyze the dynamics of the model and demonstrate that with carefully tuned synaptic connections it can accurately integrate a large range of the vestibular input, with potentially slow synapses.

  8. Ultrafast ring-opening/closing and deactivation channels for a model spiropyran-merocyanine system.

    PubMed

    Sanchez-Lozano, Marta; Estévez, Carlos Manuel; Esté vez, Carlos Manuel; Hermida-Ramón, Jose; Hermida-Ramó n, Jose; Serrano-Andres, Luis

    2011-08-25

    The photochemistry of a model merocyanine-spiropyran system was analyzed theoretically at the MS-CASPT2//SA-CASSCF(14,12) level. Several excited singlet states were studied in both the closed spiropyran and open merocyanine forms, and the paths to the different S(1)/S(0) conical intersections found were analyzed. After absorption of UV light from the spiropyran form, there are two possible ultrafast routes to efficient conversion to the ground state; one involves the rupture of the C(spiro)-O bond leading to the open form and the other involves the lengthening of the C(spiro)-N bond with no photoreaction. From the merocyanine side the excited state can reach a very broad S(1)/S(0) conical intersection region that leads the system to the closed form after rotation of the central methine bond. Alternatively, rotation of the other methine bonds connects the system through different S(1)/S(0) conical intersections to several merocyanine isomers. The present work provides a theoretical framework for the recent experimental results (Buback , J. J. Am. Chem. Soc. 2010, 132, 1610-1619) and sheds light on the complex photochemistry of these kinds of compounds.

  9. Cavity-locked ring down spectroscopy

    DOEpatents

    Zare, Richard N.; Paldus, Barbara A.; Harb, Charles C.; Spence, Thomas

    2000-01-01

    Distinct locking and sampling light beams are used in a cavity ring-down spectroscopy (CRDS) system to perform multiple ring-down measurements while the laser and ring-down cavity are continuously locked. The sampling and locking light beams have different frequencies, to ensure that the sampling and locking light are decoupled within the cavity. Preferably, the ring-down cavity is ring-shaped, the sampling light is s-polarized, and the locking light is p-polarized. Transmitted sampling light is used for ring-down measurements, while reflected locking light is used for locking in a Pound-Drever scheme.

  10. Saturn's Rings Edge-on

    NASA Technical Reports Server (NTRS)

    1995-01-01

    In one of nature's most dramatic examples of 'now-you see-them, now-you-don't', NASA's Hubble Space Telescope captured Saturn on May 22, 1995 as the planet's magnificent ring system turned edge-on. This ring-plane crossing occurs approximately every 15 years when the Earth passes through Saturn's ring plane.

    For comparison, the top picture was taken by Hubble on December 1, 1994 and shows the rings in a more familiar configuration for Earth observers.

    The bottom picture was taken shortly before the ring plane crossing. The rings do not disappear completely because the edge of the rings reflects sunlight. The dark band across the middle of Saturn is the shadow of the rings cast on the planet (the Sun is almost 3 degrees above the ring plane.) The bright stripe directly above the ring shadow is caused by sunlight reflected off the rings onto Saturn's atmosphere. Two of Saturn's icy moons are visible as tiny starlike objects in or near the ring plane. They are, from left to right, Tethys (slightly above the ring plane) and Dione.

    This observation will be used to determine the time of ring-plane crossing and the thickness of the main rings and to search for as yet undiscovered satellites. Knowledge of the exact time of ring-plane crossing will lead to an improved determination of the rate at which Saturn 'wobbles' about its axis (polar precession).

    Both pictures were taken with Hubble's Wide Field Planetary Camera 2. The top image was taken in visible light. Saturn's disk appears different in the bottom image because a narrowband filter (which only lets through light that is not absorbed by methane gas in Saturn's atmosphere) was used to reduce the bright glare of the planet. Though Saturn is approximately 900 million miles away, Hubble can see details as small as 450 miles across.

    The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science

  11. On Necessary and Sufficient Conditions for Regulation of Linear Systems Over Rings,

    DTIC Science & Technology

    1980-10-09

    book (e.g., Bourbaki [1972, Chapt. 2]). Let (m&Ii, be the set of maximal ideals of k[z, zI] such that (2.11) rank [zl - F, G]g< n. After these...Khargonekar [1980], where a . theory of observers and coefficient assignment by causal dynamic state feedback was developed. Although the split condition is...this research was done when the author was at the Center for Mathematical System Theory , University of Florida, Gainesville. Florida 32611, and was

  12. Exciton interference revealed by energy dependent exciton transfer rate for ring-structured molecular systems

    SciTech Connect

    Yan, Yun-An

    2016-01-14

    The quantum interference is an intrinsic phenomenon in quantum physics for photon and massive quantum particles. In principle, the quantum interference may also occur with quasi-particles, such as the exciton. In this study, we show how the exciton quantum interference can be significant in aggregates through theoretical simulations with hierarchical equations of motion. The systems under investigation are generalized donor-bridge-acceptor model aggregates with the donor consisting of six homogeneous sites assuming the nearest neighbor coupling. For the models with single-path bridge, the exciton transfer time only shows a weak excitation energy dependence. But models with double-path bridge have a new short transfer time scale and the excitation energy dependence of the exciton transfer time assumes clear peak structure which is detectable with today’s nonlinear spectroscopy. This abnormality is attributed to the exciton quantum interference and the condition for a clear observation in experiment is also explored.

  13. Lactones 41. Synthesis and microbial hydroxylation of unsaturated terpenoid lactones with p-menthane ring systems.

    PubMed

    Grudniewska, Aleksandra; Wawrzeńczyk, Czesław

    2013-03-01

    Racemic [(±)-4-isopropyl-1-methyl-7-oxa-cis-bicyclo[4.3.0]non-4-en-8-one] and optically active δ,ε-unsaturated lactones [(-)-(1R,6R)-4-isopropyl-1-methyl-7-oxabicyclo[4.3.0]non-4-en-8-one and (+)-(1S,6S)-4-isopropyl-1-methyl-7-oxabicyclo[4.3.0] non-4-en-8-one)] with the p-menthane system were obtained and their odoriferous properties were evaluated. Biotransformations of the racemic lactone with three fungal strains: Absidia cylindrospora AM336, Absidia glauca AM177 and Syncephalastrum racemosum AM105, were carried out. Microbial transformations afforded hydroxylactones with the hydroxy group in the allylic position.

  14. A Diastereoselective Intramolecular Pauson-Khand Approach to the Construction of the BC Ring System in Tuberostemoninol

    PubMed Central

    Jia, Xiangna; Williams, Robert M

    2009-01-01

    Herein we describe an asymmetric approach to the synthesis of a BC-ring synthon in tuberostemoninol via an intramolecular Pauson-Khand reaction stereocontrolled by a commercially available chiral glycinate. PMID:19779590

  15. Compact stellar systems in the polar ring galaxies NGC 4650A and NGC 3808B: Clues to polar disk formation

    NASA Astrophysics Data System (ADS)

    Ordenes-Briceño, Yasna; Georgiev, Iskren Y.; Puzia, Thomas H.; Goudfrooij, Paul; Arnaboldi, Magda

    2016-01-01

    Context. Polar ring galaxies (PRGs) are composed of two kinematically distinct and nearly orthogonal components, a host galaxy (HG) and a polar ring/disk (PR). The HG usually contains an older stellar population than the PR. The suggested formation channel of PRGs is still poorly constrained. Suggested options are merger, gas accretion, tidal interaction, or a combination of both. Aims: To constrain the formation scenario of PRGs, we study the compact stellar systems (CSSs) in two PRGs at different evolutionary stages: NGC 4650A with well-defined PR, and NGC 3808 B, which is in the process of PR formation. Methods: We use archival HST/WFPC2 imaging in the F450W, F555W, or F606W and F814W filters. Extensive completeness tests, PSF-fitting techniques, and color selection criteria are used to select cluster candidates. Photometric analysis of the CSSs was performed to determine their ages and masses using stellar population models at a fixed metallicity. Results: Both PRGs contain young CSSs (<1 Gyr) with masses of up to 5 × 106M⊙, mostly located in the PR and along the tidal debris. The most massive CSSs may be progenitors of metal-rich globular clusters or ultra compact dwarf (UCD) galaxies. We identify one such young UCD candidate, NGC 3808 B-8, and measure its size of reff = 25.23+1.43-2.01 pc. We reconstruct the star formation history of the two PRGs and find strong peaks in the star formation rate (SFR, ≃200 M⊙/yr) in NGC 3808 B, while NGC 4650 A shows milder (declining) star formation (SFR< 10 M⊙/yr). This difference may support different evolutionary paths between these PRGs. Conclusions: The spatial distribution, masses, and peak star formation epoch of the clusters in NGC 3808 suggest for a tidally triggered star formation. Incompleteness at old ages prevents us from probing the SFR at earlier epochs of NGC 4650 A, where we observe the fading tail of CSS formation. This also impedes us from testing the formation scenarios of this PRG.

  16. Synthesis and Characterization of High Performance Polyimides Containing the Bicyclo(2.2.2)oct-7-ene Ring System

    NASA Technical Reports Server (NTRS)

    Alvarado, M.; Harruna, I. I.; Bota, K. B.

    1997-01-01

    Due to the difficulty in processing polyimides with high temperature stability and good solvent resistance, we have synthesized high performance polyimides with bicyclo(2.2.2)-oct-7-ene ring system which can easily be fabricated into films and fibers and subsequently converted to the more stable aromatic polyimides. In order to improve processability, we prepared two polyimides by reacting 1,4-phenylenediamine and 1,3phenylediamine with bicyclo(2.2.2)-7-octene-2,3,5,6-tetracarboxylic dianhydride. The polyimides were characterized by FTIR, FTNMR, solubility and thermal analysis. Thermogravimetric analysis (TGA) showed that the 1,4-phenylenediamine and 1,3-phenylenediamine containing polyimides were stable up to 460 and 379 C, respectively under nitrogen atmosphere. No melting transitions were observed for both polyimides. The 1,4-phenylenediamine containing polyimide is partially soluble in dimethyl sulfoxide, methane sulfonic acid and soluble in sulfuric acid at room temperature. The 1,3-phenylenediamine containing polyimide is partially soluble in dimethyl sulfoxide, tetramethyl urea, N,N-dimethyl acetamide and soluble in methane sulfonic acid and sulfuric acid.

  17. High Precision 13C/12C Measurement of Dissolved Carbon Using a Transportable Cavity Ring-Down Spectrophotometer System

    NASA Astrophysics Data System (ADS)

    Saad, N.; Crosson, E.

    2009-05-01

    We report here on the measurement of high precision δ13C from total inorganic carbon (TIC) and dissolved organic carbon (DOC) using a sample preparation system coupled to a small footprint Wavelength- Scanned Cavity Ring-Down Spectrometer (WS-CRDS). This system is capable of applying a 5% H3PO4 solution or a sodium persulfate oxidation process to a water sample in an exetainer vial, thereby liberating gaseous CO2 and permitting stable carbon isotope measurement in TIC and DOC, respectively. The isotopic carbon signature determination can then be used to trace the origin of carbonates or organic carbon compounds. In a first phase, a manual process was employed in which TIC containing samples were acidified and the evolved CO2 was collected inside gas pillows. The gas pillows were then connected to the inlet of the isotopic WS-CRDS instrument for carbon ratio measurement. In a second phase, the CO2 liberation processes were automated in an integrated analyzer enabling software control of a sample preparation system directly connected to the gas inlet of the isotopic WS-CRDS instrument. A measurement precision of the isotopic ratio in the range of 0.2 to 0.4 permil was achieved in minutes of measurement time. Such precision readily distinguishes the isotopic TIC and DOC signatures from a set of three different stream water samples collected from various sites in Northern California. The current TIC/DOC- CRDS setup will enable shipboard measurement and presents a rugged, portable and inexpensive analytical instrumentation alternative to the traditional use of methods based on the more complex and lab-confined isotope ratio mass spectrometry technique.

  18. A novel FPGA-based bunch purity monitor system at the APS storage ring.

    SciTech Connect

    Norum, W. E.; APS Engineering Support Division

    2008-01-01

    Bunch purity is an important source quality factor for the magnetic resonance experiments at the Advanced Photon Source. Conventional bunch-purity monitors utilizing time-to-amplitude converters are subject to dead time. We present a novel design based on a single field- programmable gate array (FPGA) that continuously processes pulses at the full speed of the detector and front-end electronics. The FPGA provides 7778 single-channel analyzers (six per rf bucket). The starting time and width of each single-channel analyzer window can be set to a resolution of 178 ps. A detector pulse arriving inside the window of a single-channel analyzer is recorded in an associated 32-bit counter. The analyzer makes no contribution to the system dead time. Two channels for each rf bucket count pulses originating from the electrons in the bucket. The other four channels on the early and late side of the bucket provide estimates of the background. A single-chip microcontroller attached to the FPGA acts as an EPICS IOC to make the information in the FPGA available to the EPICS clients.

  19. Study of the use of methanol-filled Er-doped suspended-core fibres in a temperature-sensing ring laser system

    NASA Astrophysics Data System (ADS)

    Martín, J. C.; Berdejo, V.; Vallés, J. A.; Sánchez-Martín, J. A.; Díez, A.; Andrés, M. V.

    2013-10-01

    We report on an experimental/numerical investigation into the use of methanol-filled Er-doped suspended-core fibres (SCFs) in temperature-sensing ring laser systems. We have adopted a ring laser configuration that includes an Er-doped SCF as a temperature-dependent attenuator (TDA) with a step-index Er-doped fibre (EDF) as the laser active medium. The laser performance dependence on the temperature was measured both in continuous wave (CW) and transient regimes. CW laser output power and build-up time values are compared with those of similar laser systems based on other types of Er-doped PCFs or using other laser configurations. A notable variation of 0.73% °C-1 was achieved in CW operation. Then, by means of parameters obtained by numerically fitting the experimental results, the potential sensing performance of the laser configuration with an SCF as a TDA is studied. Moreover, two ring cavity laser configurations (with the SCF acting basically as an attenuator or also as the active media) are compared and the influence of the position of the coupler inside the ring cavity and the contribution of the erbium doping to improve the sensor features are analysed. The longer interaction lengths compatible with laser action using the Er-doped SCF as a TDA could provide variations of laser output power up to 8.6% °C-1 for 90 mW pump power and a 1 m methanol-filled SCF.

  20. Belt-hierarchic structure of th ring, satellite and planet systems: prediction S/2001 U1 and others objects in Solar system

    NASA Astrophysics Data System (ADS)

    Barkin, Yu. V.

    2003-04-01

    BELT-HIERARCHIC STRUCTURE OF THE RING, SATELLITE AND PLANET SYSTEMS: PREDICTION S/2001 U1 AND OTHERS OBJECTS IN SOLAR SYSTEM Yu.V.Barkin Sternberg Astronomical Institute, Moscow, Russia, barkin@sai.msu.ru Structure regularities of the planet and satellite systems have been studied. Statistic analysis of the distribution of the major semi-axes of the orbits of the planets, comets and centaurs of the Solar system, satellite and ring systems of Jupiter, Saturn, Neptune and Uran, exoplanet systems of the pulsars PSR 1257+12, PSR 1828-11 and of the main consequence star Ups And was fulfilled. The following empirical regularities were described [1]: 1) the bodies of systems are combined into hierarchic groups and main from them combine 5 companions; 2) differences of the major semi-axes of the neighboring orbits for bodies of every group are constant; 4) for main neighboring hierarchic group these distances are distinguished in 6 times increasing to external grope; 5) the filling of the gropes and some present changes in their structure are caused by the past catastrophes in corresponding systems. The special method of reconstruction of the catastrophes which had place in the life of the Solar system (SS) was developed. Suggested method has let us to explain uniformly observed values of the major semi-axes and average values of eccentricities of the planets. In particular the Pancul’s hypothesis about Jupiter formation from two giant protoplanets (Jupiter I and Jupiter II) was confirmed. The new empirical law of the filling of the orbits of the regular groups of the planets or satellites (or rings structures) of the hierarchic ordered systems of celestial bodies was established. It was shown that sum number of bodies is proportional to the value of catastrophic value of the eccentricities which are same for first, second ,.... and fifth orbits of all gropes. The theoretical numbers of bodies for pointed orbits practically coincide with their observed numbers in main

  1. Saturn Ring Observer

    NASA Technical Reports Server (NTRS)

    Spilker, T. R.

    2001-01-01

    Answering fundamental questions about ring particle characteristics, and individual and group behavior, appears to require close-proximity (a few km) observations. Saturn's magnificent example of a ring system offers a full range of particle sizes, densities, and behaviors for study, so it is a natural choice for such detailed investigation. Missions implementing these observations require post-approach Delta(V) of approximately 10 km/s or more, so past mission concepts called upon Nuclear Electric Propulsion. The concept described here reduces the propulsive Delta(V) requirement to as little as 3.5 km/s, difficult but not impossible for high-performance chemical propulsion systems. Additional information is contained in the original extended abstract.

  2. Ringing phenomenon of the fiber ring resonator.

    PubMed

    Ying, Diqing; Ma, Huilian; Jin, Zhonghe

    2007-08-01

    A resonator fiber-optic gyro (R-FOG) is a high-accuracy inertial rotation sensor based on the Sagnac effect. A fiber ring resonator is the core sensing element in the R-FOG. When the frequency of the fiber ring resonator input laser is swept linearly with time, ringing of the output resonance curve is observed. The output field of the fiber ring resonator is derived from the superposition of the light transmitted through the directional coupler directly and the multiple light components circulated in the fiber ring resonator when the frequency of the laser is swept. The amplitude and phase of the output field are analyzed, and it is found that the difference in time for different light components in the fiber ring resonator to reach a point of destructive interference causes the ringing phenomenon. Finally the ringing phenomenon is observed in experiments, and the experimental results agree with the theoretical analysis well.

  3. GPU-based low-level trigger system for the standalone reconstruction of the ring-shaped hit patterns in the RICH Cherenkov detector of NA62 experiment

    NASA Astrophysics Data System (ADS)

    Ammendola, R.; Biagioni, A.; Chiozzi, S.; Cretaro, P.; Cotta Ramusino, A.; Di Lorenzo, S.; Fantechi, R.; Fiorini, M.; Frezza, O.; Gianoli, A.; Lamanna, G.; Lo Cicero, F.; Lonardo, A.; Martinelli, M.; Neri, I.; Paolucci, P. S.; Pastorelli, E.; Piandani, R.; Piccini, M.; Pontisso, L.; Rossetti, D.; Simula, F.; Sozzi, M.; Vicini, P.

    2017-03-01

    This project aims to exploit the parallel computing power of a commercial Graphics Processing Unit (GPU) to implement fast pattern matching in the Ring Imaging Cherenkov (RICH) detector for the level 0 (L0) trigger of the NA62 experiment. In this approach, the ring-fitting algorithm is seedless, being fed with raw RICH data, with no previous information on the ring position from other detectors. Moreover, since the L0 trigger is provided with a more elaborated information than a simple multiplicity number, it results in a higher selection power. Two methods have been studied in order to reduce the data transfer latency from the readout boards of the detector to the GPU, i.e., the use of a dedicated NIC device driver with very low latency and a direct data transfer protocol from a custom FPGA-based NIC to the GPU. The performance of the system, developed through the FPGA approach, for multi-ring Cherenkov online reconstruction obtained during the NA62 physics runs is presented.

  4. The Saturn Ring Observer: In situ studies of planetary rings

    NASA Astrophysics Data System (ADS)

    Nicholson, P. D.; Tiscareno, M. S.; Spilker, L. J.

    2010-12-01

    targets of observation by the SRO will include “propellers” (thought to be the signature of sub-km moonlets embedded in the rings), the “ropy” and “straw” structure seen in images of strong density waves and gap edges, and km-scale radial oscillations which may be signatures of “viscous overstabilities” in high-optical depth regions. Most of the science goals identified above could be accomplished by high-resolution nadir imaging of the rings from a platform that co-orbits with the ring particles, i.e., from a spacecraft in circular orbit a few km above the rings. The vertical displacement of the spacecraft is maintained by a continuous low-thrust ion engine, which can be tilted to provide a slow inward radial drift across the rings. Chemical thrusters permit the craft to `hop' over vertical obstacles in the rings (e.g., bending waves and inclined ringlets). In addition to an imaging system with a resolution of at least 10 cm (with 1 cm a desirable goal), other instrumentat ion might include a laser altimeter/range-finder to measure the effective thickness of the rings, as well as the vertical component of particle motions, aswell as in situ instruments to measure the density and composition of the neutral and ionized ring atmosphere, meteoritic and secondary dust fluxes, and local electric fields (especially in spoke regions).

  5. Asymmetric dipolar ring

    DOEpatents

    Prosandeev, Sergey A.; Ponomareva, Inna V.; Kornev, Igor A.; Bellaiche, Laurent M.

    2010-11-16

    A device having a dipolar ring surrounding an interior region that is disposed asymmetrically on the ring. The dipolar ring generates a toroidal moment switchable between at least two stable states by a homogeneous field applied to the dipolar ring in the plane of the ring. The ring may be made of ferroelectric or magnetic material. In the former case, the homogeneous field is an electric field and in the latter case, the homogeneous field is a magnetic field.

  6. Functional diversification of the RING finger and other binuclear treble clef domains in prokaryotes and the early evolution of the ubiquitin system.

    PubMed

    Burroughs, A Maxwell; Iyer, Lakshminarayan M; Aravind, L

    2011-07-01

    Recent studies point to a diverse assemblage of prokaryotic cognates of the eukaryotic ubiquitin (Ub) system. These systems span an entire spectrum, ranging from those catalyzing cofactor and amino acid biosynthesis, with only adenylating E1-like enzymes and ubiquitin-like proteins (Ubls), to those that are closer to eukaryotic systems by virtue of possessing E2 enzymes. Until recently E3 enzymes were unknown in such prokaryotic systems. Using contextual information from comparative genomics, we uncover a diverse group of RING finger E3s in prokaryotes that are likely to function with E1s, E2s, JAB domain peptidases and Ubls. These E1s, E2s and RING fingers suggest that features hitherto believed to be unique to eukaryotic versions of these proteins emerged progressively in such prokaryotic systems. These include the specific configuration of residues associated with oxyanion-hole formation in E2s and the C-terminal UFD in the E1 enzyme, which presents the E2 to its active site. Our study suggests for the first time that YukD-like Ubls might be conjugated by some of these systems in a manner similar to eukaryotic Ubls. We also show that prokaryotic RING fingers possess considerable functional diversity and that not all of them are involved in Ub-related functions. In eukaryotes, other than RING fingers, a number of distinct binuclear (chelating two Zn atoms) and mononuclear (chelating one zinc atom) treble clef domains are involved in Ub-related functions. Through detailed structural analysis we delineated the higher order relationships and interaction modes of binuclear treble clef domains. This indicated that the FYVE domain acquired the binuclear state independently of the other binuclear forms and that different treble clef domains have convergently acquired Ub-related functions independently of the RING finger. Among these, we uncover evidence for notable prokaryotic radiations of the ZF-UBP, B-box, AN1 and LIM clades of treble clef domains and present

  7. Latitudinal gradients in tree ring stable carbon and oxygen isotopes reveal differential climate influences of the North American Monsoon System

    NASA Astrophysics Data System (ADS)

    Szejner, Paul; Wright, William E.; Babst, Flurin; Belmecheri, Soumaya; Trouet, Valerie; Leavitt, Steven W.; Ehleringer, James R.; Monson, Russell K.

    2016-07-01

    The arrival of the North American Monsoon System (NAMS) terminates a presummer hyperarid period in the southwestern United States (U.S.), providing summer moisture that is favorable for forest growth. Montane forests in this region rely on winter snowpack to drive much of their growth; the extent to which they use NAMS moisture is uncertain. We addressed this by studying stable carbon and oxygen isotopes in earlywood and latewood from 11 sites along a latitudinal gradient extending from Arizona and New Mexico to Utah. This study provides the first regional perspective on the relative roles of winter versus summer precipitation as an ecophysiological resource. Here we present evidence that Ponderosa pine uses NAMS moisture differentially across this gradient. 13C/12C ratios suggest that photosynthetic water use efficiency during latewood formation is more sensitive to summer precipitation at the northern than at the southern sites. This is likely due to the fact that NAMS moisture provides sufficiently favorable conditions for tree photosynthesis and growth during most years in the southern sites, whereas the northern sites experience larger summer moisture variability, which in some years is limiting growth. Cellulose δ18O and δ13C values revealed that photoassimilates in the southern sites were produced under higher vapor pressure deficit conditions during spring compared to summer, demonstrating a previously underappreciated effect of seasonal differences in atmospheric humidity on tree ring isotope ratios. Our findings suggest that future changes in NAMS will potentially alter productivity and photosynthetic water use dynamics differentially along latitudinal gradients in southwestern U.S. montane forests.

  8. From the Icy Satellites to Small Moons and Rings: Spectral Indicators by Cassini-VIMS Unveil Compositional Trends in the Saturnian System

    NASA Astrophysics Data System (ADS)

    Filacchione, G.; Capaccioni, F.; Ciarniello, M.; Nicholson, P. D.; Clark, R. N.; Cuzzi, J. N.; Buratti, B. B.; Cruikshank, D. P.; Brown, R. H.

    2017-01-01

    flat reflectance in the visible, making them remarkably different with respect to the other small moons. Moreover, we have observed that the two Tethys' lagrangian moons appear spectrally different, with Calypso characterized by more intense water ice bands than Telesto. Conversely, at visible wavelengths Polydeuces, Telesto and Methone are in absolute the more blue objects in the Saturn's system. The red slopes measured in the visible range on disk-integrated spectral data, showing varying degrees on all of the satellites, could be caused more by exogenic processes than by geologic and endogenic events which are operating on more localized scales. The principal exogenic processes active in the Saturn's system [11] which alter the satellites and rings surfaces are the E ring particles bombardment, the interaction with corotating plasma and energetic particles, the bombardment of exogenic dark material [12] and the water ice photolysis. A discussion about the correlations between these processes and the o bserved spectral classes is given. With the approaching of the Cassini "Gran Finale" orbits, VIMS will unveil with unprecedented spatial resolution the spectral properties of many small moons and rings. These data will be extremely valuable to improve our classification of the Saturn's satellites and rings.

  9. Synthetic studies on schisandra nortriterpenoids. Stereocontrolled synthesis of enantiopure C-5-epi ABC ring systems of micrandilactone A and lancifodilactone G using RCM.

    PubMed

    Maity, Soumitra; Matcha, Kiran; Ghosh, Subrata

    2010-06-18

    A stereocontrolled approach for the construction of ABC ring systems of micrandilactone A and lancifodilactone G has been developed. The synthesis involves construction of an enantiopure functionalized cycloheptene derivative 17 through RCM of the dienol 14 prepared from the known D-mannitol-derived unsaturated ester 12. A remarkable regioselectivity during hydroboration of the cycloheptene derivative 17 was observed during its transformation to the cycloheptanone 20. RCM of the diene 24 prepared stereoselectively from 20 gave the spiro-dihydrofuran 25. The ketal unit in 25 was then converted into the carbinols 28 and 36. A bromonium ion initiated highly stereocontrolled intramolecular etherification in 28 and 37 led to the tricyclic ethers 29 and 38, respectively. Reductive removal of bromine from 29 and 38 followed by RuO(4) oxidation led to the furo-furanone derivatives 31 and 40, the C-5-epi ABC ring systems of the schisandra nortriterpenoids 1 and 2.

  10. Combined Brillouin light scattering and microwave absorption study of magnon-photon coupling in a split-ring resonator/YIG film system

    NASA Astrophysics Data System (ADS)

    Klingler, S.; Maier-Flaig, H.; Gross, R.; Hu, C.-M.; Huebl, H.; Goennenwein, S. T. B.; Weiler, M.

    2016-08-01

    Microfocused Brillouin light scattering (BLS) and microwave absorption (MA) are used to study magnon-photon coupling in a system consisting of a split-ring microwave resonator and an yttrium iron garnet (YIG) film. The split-ring resonator is defined by optical lithography and loaded with a 1 μm-thick YIG film grown by liquid phase epitaxy. BLS and MA spectra of the hybrid system are simultaneously recorded as a function of the applied magnetic field magnitude and microwave excitation frequency. Strong coupling of the magnon and microwave resonator modes is found with a coupling strength of geff /2π = 63 MHz. The combined BLS and MA data allow us to study the continuous transition of the hybridized modes from a purely magnonic to a purely photonic mode by varying the applied magnetic field and microwave frequency. Furthermore, the BLS data represent an up-conversion of the microwave frequency coupling to optical frequencies.

  11. Structure-activity relationship studies on anti-HCV activity of ring-expanded (‘fat’) nucleobase analogues containing the imidazo[4,5-e][1,3]diazepine-4,8-dione ring system

    PubMed Central

    Zhang, Peng; Zhang, Ning; Korba, Brent E.; Hosmane, Ramachandra S.

    2009-01-01

    In continuation of our structure-activity relationship studies on anti-HCV activity of the title imidazo[4,5-e][1,3]diazepine ring system, we report here the synthesis and effect on biological activity of introducing hydrophobic substituents at the 2-position of the heterocycle. Our results suggest that there is no particular advantage to that end as the observed antiviral activity of the test compounds was lower than the unmodified 2-bromo derivative used for comparison. The activity/toxicity profile of all target compounds, however, was still better than the reference compound ribavirin used in the antiviral assay, but not as good as that of interferon-α, the other reference compound used in the assay. PMID:17300935

  12. Recent Developments of Versatile Photoinitiating Systems for Cationic Ring Opening Polymerization Operating at Any Wavelengths and under Low Light Intensity Sources.

    PubMed

    Lalevée, Jacques; Mokbel, Haifaa; Fouassier, Jean-Pierre

    2015-04-20

    Photoinitiators (PI) or photoinitiating systems (PIS) usable in light induced cationic polymerization (CP) and free radical promoted cationic polymerization (FRPCP) reactions (more specifically for cationic ring opening polymerization (ROP)) together with the involved mechanisms are briefly reviewed. The recent developments of novel two- and three-component PISs for CP and FRPCP upon exposure to low intensity blue to red lights is emphasized in details. Examples of such reactions under various experimental conditions are provided.

  13. From Satellites to Rings: The Diversity of the Saturnian System Ices in the VIS-NIR at the End of Cassini-VIMS Nominal Mission

    NASA Astrophysics Data System (ADS)

    Filacchione, Gianrico; Capaccioni, F.; Tosi, F.; Coradini, A.; Cerroni, P.; Clark, R. N.; Cuzzi, J. N.; Cruikshank, D. P.; Nicholson, P. D.; Hedman, M. M.; McCord, T. B.; Brown, R. H.; Buratti, B. J.; Jaumann, R.; Stephan, K.

    2008-09-01

    After four years of nominal mission, VIMS has observed the whole population of Saturnian icy objects allowing a comparative analysis of the VIS-NIR spectral properties of the regular satellites (Mimas, Enceladus, Tethys, Dione, Rhea, Hyperion, Iapetus, Phoebe), minor moons (Atlas, Prometheus, Pandora, Janus, Epimetheus, Telesto, Calypso) and main rings (A, B, C and Cassini division). The results we present are derived from the whole dataset available at june 2008 which consists of about 1500 full-disk observations of the moons as well as several radial mosaics of the ring system. The most important spectrophotometric indicators (I/F continua, VIS spectral slopes, water and carbon dioxide IR bands strengths and positions) are calculated for each observation in order to identify the disk-integrated compositional units of the satellites, the distribution of water ice respect to "contaminants” abundances and typical regolith grain properties for both satellites and rings. These quantities are varying between the almost pure water ice surfaces of Enceladus and Calypso to the organic and carbon dioxide rich Hyperion, Iapetus and Phoebe. Some significant differences are detected in the VIS colors of co-orbital moons Epimetheus and Janus, with the first very red and therefore similar to Hyperion while the last is more "neutral” these results could help to decipher the origins and evolutional story of these two moons. The water ice band strengths of the A-B rings are the most intense of the Saturnian system denoting a minimal presence of "contaminants” which can be estimated thanks to the 350-520 nm spectral slope. Finally we compare these spectral parameters with some TNOs and outer solar system objects (1995UG5, 90377-Sedna, 1996TO66, Pholus, Triton, Charon, Oberon, Titania) to search for possible analogies. This research was possible thanks to the support of the Italian Space Agency (ASI).

  14. Which Ringed Planet...!?

    NASA Astrophysics Data System (ADS)

    2002-12-01

    Don't worry - you are not the only one who thought this was a nice amateur photo of planet Saturn, Lord of the Rings in our Solar System! But then the relative brightness and positions of the moons may appear somewhat unfamiliar... and the ring system does look unusually bright when compared to the planetary disk...?? Well, it is not Saturn, but Uranus , the next giant planet further out, located at a distance of about 3,000 million km, or 20 times the distance between the Sun and the Earth. The photo shows Uranus surrounded by its rings and some of the moons, as they appear on a near-infrared image that was obtained in the K s -band (at wavelength 2.2 µm) with the ISAAC multi-mode instrument on the 8.2-m VLT ANTU telescope at the ESO Paranal Observatory (Chile) . The exposure was made on November 19, 2002 (03:00 hrs UT) during a planetary research programme. The observing conditions were excellent (seeing 0.5 arcsec) and the exposure lasted 5 min. The angular diameter of Uranus is about 3.5 arcsec. The observers at ISAAC were Emmanuel Lellouch and Thérése Encrenaz of the Observatoire de Paris (France) and Jean-Gabriel Cuby and Andreas Jaunsen (both ESO-Chile). The rings The rings of Uranus were discovered in 1977, from observations during a stellar occultation event by astronomer teams at the Kuiper Airborne Observatory (KAO) and the Perth Observatory (Australia). Just before and after the planet moved in front of the (occulted) star, the surrounding rings caused the starlight to dim for short intervals of time. Photos obtained from the Voyager-2 spacecraft in 1986 showed a multitude of very tenuous rings. These rings are almost undetectable from the Earth in visible light. However, on the present VLT near-infrared picture, the contrast between the rings and the planet is strongly enhanced. At the particular wavelength at which this observation was made, the infalling sunlight is almost completely absorbed by gaseous methane present in the planetary atmosphere

  15. Stirling engine piston ring

    DOEpatents

    Howarth, Roy B.

    1983-01-01

    A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

  16. Birth Control Ring

    MedlinePlus

    ... Loss Surgery? A Week of Healthy Breakfasts Shyness Birth Control Ring KidsHealth > For Teens > Birth Control Ring Print A A A What's in this ... español Anillo vaginal anticonceptivo What Is It? The birth control ring is a soft, flexible, doughnut-shaped ring ...

  17. Does the position of the electron-donating nitrogen atom in the ring system influence the efficiency of a dye-sensitized solar cell? A computational study.

    PubMed

    Biswas, Abul Kalam; Barik, Sunirmal; Das, Amitava; Ganguly, Bishwajit

    2016-06-01

    We have reported a number of new metal-free organic dyes (2-6) that have cyclic asymmetric benzotripyrrole derivatives as donor groups with peripheral nitrogen atoms in the ring, fluorine and thiophene groups as π-spacers, and a cyanoacrylic acid acceptor group. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were employed to examine the influence of the position of the donor nitrogen atom and π-conjugation on solar cell performance. The calculated electron-injection driving force (ΔG inject), electron-regeneration driving force (ΔG regen), light-harvesting efficiency (LHE), dipole moment (μ normal), and number of electrons transferred (∆q) indicate that dyes 3, 4, and 6 have significantly higher efficiencies than reference dye 1, which exhibits high efficiency. We also extended our comparison to some other reported dyes, 7-9, which have a donor nitrogen atom in the middle of the ring system. The computed results suggest that dye 6 possesses a higher incident photon to current conversion efficiency (IPCE) than reported dyes 7-9. Thus, the use of donor groups with peripheral nitrogen atoms appears to lead to more efficient dyes than those in which the nitrogen atom is present in the middle of the donor ring system. Graphical Abstract The locations of the nitrogen atoms in the donor groups in the designed dye molecules have an important influence on DSSC efficiency.

  18. NMR measurement system including two synchronized ring buffers, with 128 rf coils for in situ water monitoring in a polymer electrolyte fuel cell.

    PubMed

    Ogawa, Kuniyasu; Haishi, Tomoyuki; Aoki, Masaru; Hasegawa, Hiroshi; Morisaka, Shinichi; Hashimoto, Seitaro

    2017-01-01

    A small radio-frequency (rf) coil inserted into a polymer electrolyte fuel cell (PEFC) can be used to acquire nuclear magnetic resonance (NMR) signals from the water in a membrane electrode assembly (MEA) or in oxygen gas channels in the PEFC. Measuring the spatial distribution of the water in a large PEFC requires using many rf probes, so an NMR measurement system which acquires NMR signals from 128 rf probes at intervals of 0.5 s was manufactured. The system has eight rf transceiver units with a field-programmable gate array (FPGA) for modulation of the excitation pulse and quadrature phase detection of the NMR signal, and one control unit with two ring buffers for data control. The sequence data required for the NMR measurement were written into one ring buffer. The acquired NMR signal data were then written temporarily into the other ring buffer and then were transmitted to a personal computer (PC). A total of 98 rf probes were inserted into the PEFC that had an electrical generation area of 16 cm × 14 cm, and the water generated in the PEFC was measured when the PEFC operated at 100 A. As a result, time-dependent changes in the spatial distribution of the water content in the MEA and the water in the oxygen gas channels were obtained.

  19. Spin transfer in a ferromagnet-quantum dot and tunnel-barrier-coupled Aharonov-Bohm ring system with Rashba spin-orbit interactions.

    PubMed

    Chen, Xi; Zheng, Qing-Rong; Su, Gang

    2010-05-12

    The spin transfer effect in a ferromagnet-quantum dot (insulator)-ferromagnet Aharonov-Bohm (AB) ring system with Rashba spin-orbit (SO) interactions is investigated by means of the Keldysh nonequilibrium Green function method. It is found that both the magnitude and direction of the spin transfer torque (STT) acting on the right ferromagnet electrode can be effectively controlled by changing the magnetic flux threading the AB ring or the gate voltage on the quantum dot. The STT can be greatly augmented by matching a proper magnetic flux and an SO interaction at a cost of low electrical current. The STT, electrical current and spin current are uncovered to oscillate with the magnetic flux. The present results are expected to be useful for information storage in nanospintronics.

  20. New Dust Belts of Uranus: One Ring, Two Ring, Red Ring, Blue Ring

    SciTech Connect

    de Pater, I; Hammel, H B; Gibbard, S G; Showalter, M R

    2006-02-02

    We compare near-infrared observations of the recently discovered outer rings of Uranus with HST results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/2003 U 1 is probably produced via impacts into the embedded moon Mab, which apparently orbits at a location where non-gravitational perturbations favor the survival and spreading of sub-micron sized dust. R/2003 U 2 more closely resembles Saturn's G ring.

  1. Correction: El Azab, I.H., et al. Microwave-Assisted Synthesis of Novel 2H-Chromene Derivatives Bearing Phenylthiazolidinones and Their Biological Activity Assessment. Molecules 2014, 19, 19648-19664.

    PubMed

    El Azab, Islam H; Youssef, Mohamed M; Amin, Amin M

    2015-02-09

    The authors wish to revise the Author Affiliation section of the title paper, published in Molecules [1], (doi:10.3390/molecules191219648, website: http://www.mdpi.com/1420-3049/19/12/19648). To recognize the fact that the research described was performed in part at the facilities of Taif University and to acknowledge that institution's generous financial support[...].

  2. Understanding the Molecular Determinant of Reversible Human Monoamine Oxidase B Inhibitors Containing 2H-chromen-2-One Core: Structure-Based and Ligand-Based Derived 3-D QSAR Predictive Models.

    PubMed

    Mladenovic, Milan; Patsilinakos, Alexandros; Pirolli, Adele; Sabatino, Manuela; Ragno, Rino

    2017-03-14

    Monoamine oxidase B (MAO B) catalyzes the oxidative deamination of aryalkylamines neurotransmitters with concomitant reduction of oxygen to hydrogen peroxide. Consequently, the enzyme's malfunction can induce oxidative damage to mitochondrial DNA and mediates development of Parkinson's disease. Thus, MAO B emerges as a promising target for developing pharmaceuticals potentially useful to treat this vicious neurodegenerative condition. Aiming to contribute to the development of drugs with the reversible mechanism of MAO B inhibition only, herein, an extended in silico-in vitro procedure for the selection of novel MAO B inhibitors is demonstrated, including: (1) definition of optimized and validated structure-based (SB) 3-D QSAR models derived from available co-crystallized inhibitor-MAO B complexes; (2) elaboration of structure-activity relationships (SAR) features for either irreversible or reversible MAO B inhibitors to characterize and improve coumarin-based inhibitor activity (Protein Data Bank ID: 2V61) as the most potent reversible lead compound; (3) definition of structure-based (SB) and ligand-based (LB) alignment rules assessments by which virtually any untested potential MAO B inhibitor might be evaluated; (4) predictive ability validation of the best 3-D QSAR model through SB/LB modeling of four coumarin-based external test sets (267 compounds); (5) design and SB/LB alignment of novel coumarin-based scaffolds experimentally validated through synthesis and biological evaluation in vitro. Due to the wide range of molecular diversity within the 3-D QSARs training set and derived features, the selected N probe-derived 3-D QSAR model proves to be a valuable tool for virtual screening (VS) of novel MAO B inhibitors and a platform for design, synthesis and evaluation of novel active structures. Accordingly, six highly active and selective MAO B inhibitors (picomolar to low nanomolar range of activity) were disclosed as a result of rational SB/LB 3-D QSAR design; therefore, D123 (IC50 = 0.83 nM, Ki =0.25 nM) and D124 (IC50 = 0.97 nM, Ki =0.29 nM) are potential lead candidates as anti-Parkinson's drugs.

  3. Spectroscopic studies, DFT calculations, and cytotoxic activity of novel silver(I) complexes of hydroxy ortho-substituted-nitro-2H-chromen-2-one ligands and a phenanthroline adduct.

    PubMed

    Mujahid, Muhammad; Kia, Agnieszka Foltyn-Arfa; Duff, Brian; Egan, Denise A; Devereux, Michael; McClean, Siobhán; Walsh, Maureen; Trendafilova, Natasha; Georgieva, Ivelina; Creaven, Bernadette S

    2015-12-01

    Silver(I) complexes of coumarin-based ligands and one of their phenanthroline (phen) adducts have been prepared and characterized using microanalytical data, molar conductivity, IR, (1)H and (13)C NMR, UV-Vis, and atomic absorption (AAS) spectroscopies. The binding modes of the coumarin-based ligands and the most probable structure of their Ag(I) complexes were predicted by means of molecular modeling and calculations of their IR, NMR, and absorption spectra using density functional theory (DFT). The cytotoxicity of the compounds studied against human-derived hepatic carcinoma cells (Hep-G2) and a renal cancer cell line (A498) showed that the complexes were more cytotoxic than the clinically used chemotherapeutic, mitoxantrone. The compounds showed little interaction with DNA and also did not show nuclease activity but manifested excellent superoxide dismutase activity which may indicate that their mechanism of action is quite different to many metal-based therapeutics.

  4. UV-laser microdissection system - A novel approach for the preparation of high-resolution stable isotope records (δ13C/δ18O) from tree rings

    NASA Astrophysics Data System (ADS)

    Schollaen, Karina; Helle, Gerhard

    2013-04-01

    Intra-annual stable isotope (δ13C and δ18O) studies of tree rings at various incremental resolutions have been attempting to extract valuable seasonal climatic and environmental information or assessing plant ecophysiological processes. For preparing high-resolution isotope samples normally wood segments or cores are mechanically divided in radial direction or cut in tangential direction. After mechanical dissection, wood samples are ground to a fine powder and either cellulose is extracted or bulk wood samples are analyzed. Here, we present a novel approach for the preparation of high-resolution stable isotope records from tree rings using an UV-laser microdissection system. Firstly, tree-ring cellulose is directly extracted from wholewood cross-sections largely leaving the wood anatomical structure intact and saving time as compared to the classical procedure. Secondly, micro-samples from cellulose cross-sections are dissected with an UV-Laser dissection microscope. Tissues of interest from cellulose cross-sections are identified and marked precisely with a screen-pen and dissected via an UV-laser beam. Dissected cellulose segments were automatically collected in capsules and are prepared for stable isotope (δ13C and δ18O) analysis. The new techniques facilitate inter- and intra-annual isotope analysis on tree-ring and open various possibilities for comparisons with wood anatomy in plant eco-physiological studies. We describe the design and the handling of this novel methodology and discuss advantages and constraints given by the example of intra-annual oxygen isotope analysis on tropical trees.

  5. Classifying Saturn's F Ring Strands

    NASA Astrophysics Data System (ADS)

    Albers, Nicole; Sremcevic, M.; Esposito, L. W.; Colwell, J. E.

    2009-09-01

    The Cassini Ultraviolet Imaging Spectrograph (UVIS) High Speed Photometer (HSP) has recorded more than 113 stellar occultations by Saturn's F ring providing measurements with ring plane resolutions of a few dozen meters and better. Inner and outer F ring strands have been seen throughout the Cassini mission where they revealed themselves as non-continuous, azimuthally and temporally highly variable structures. In the light of a more accurate orbit description of the F ring core we find evidence for a ring that becomes dynamically more active as the system approaches anti-apse alignment with Prometheus. This is consistent with the observed increased strand activity. A recent strand that morphologically resembles the core is the strongest seen to date and points to the intricate relation between core and strands indicating the strands' violent creation. Using more than 150 identifications of various strands, we trace their kinematics and infer dynamical timescales and photometric properties. Implications for the dynamical evolution of the F ring will be discussed. This research was supported by the Cassini Project.

  6. Decoding Debris System Substructures: Imprints of Planets/Planetesimals and Signatures of Extrinsic Influences on Material in Ring-Like Disks

    NASA Astrophysics Data System (ADS)

    Grady, C. A.; Schneider, Glenn; Carson, Joseph; Debes, John H.; Gaspar, Andras; Henning, Thomas; Hines, Dean C.; Hinz, Philip; Jang-Condell, Hannah; Kuchner, Marc J.; Moro-Martin, Amaya; Perrin, Marshall D.; Rodigas, T. J.; Serabyn, Gene; Silverstone, Murray D.; Stark, Christopher C.; Tamura, Motohide; Weinberger, Alycia J.; Wisniewski, John P.; Konishi, Mihoko

    2016-01-01

    How do circumstellar (CS) disks evolve and form planetary systems? Is our solar system's two-component debris disk (DD) typical? Are planets implicated by evidence of dynamical stirring in disks? Are DD architectures correlated with stellar mass? To address these highly-compelling questions of fundamental astrophysical import, we obtained deep follow-up HST/STIS coronagraphic imagery of five intermediate-inclination ring-like DDs. By combining data from two coronagraphic apertures we obtain images with unprecedented clarity, sensitivity, and photometric efficacy. We discover a scattered light counterpart to the dust disk previously seen in the mid-IR only in HD 141569 A interior to the 2 rings previously imaged in scattered light. We also place refined optical limits on planets in that system. For HR 4796 A we detect outer nebulosity extending as far as 10 arc seconds from the star, and compare it with other systems with distant dust. We report on early stages of analysis for our other 3 program stars.

  7. Intrinsic structure in Saturn's rings

    NASA Astrophysics Data System (ADS)

    Albers, N.

    2015-10-01

    Saturn's rings are the most prominent in our Solar system and one example of granular matter in space. Dominated by tides and inelastic collisions the system is highly flattened being almost 300000km wide while only tens of meters thick. Individual particles are composed of primarily water ice and range from microns to few tens of meters in size. Apparent patterns comprise ringlets, gaps, kinematic wakes, propellers, bending waves, and the winding spiral arms of density waves. These large-scale structures are perturbations foremost created by external as well as embedded moons. Observations made by the Cassini spacecraft currently in orbit around Saturn show these structures in unprecedented detail. But high-resolution measurements reveal the presence of small-scale structures throughout the system. These include self-gravity wakes (50-100m), overstable waves (100-300m), subkm structure at the A and B ring edges, "straw" and "ropy" structures (1-3km), and the C ring "ghosts". Most of these had not been anticipated and are found in perturbed regions, driven by resonances with external moons, where the system undergoes periodic phases of compression and relaxation that correlate with the presence of structure. High velocity dispersion and the presence of large clumps imply structure formation on time scales as short as one orbit (about 10 hours). The presence of these intrinsic structures is seemingly the response to varying local conditions such as internal density, optical depth, underlying particle size distribution, granular temperature, and distance from the central planet. Their abundance provides evidence for an active and dynamic ring system where aggregation and fragmentation are ongoing on orbital timescales. Thus a kinetic description of the rings may be more appropriate than the fluid one. I will present Cassini Ultraviolet Spectrometer (UVIS) High Speed Photometer (HSP) occultations, Voyager 1 and 2 Imaging Science Subsystem (ISS), and high

  8. Double-O-Ring Plug For Leak Tests

    NASA Technical Reports Server (NTRS)

    Greene, James H.

    1989-01-01

    Pressure plug features redundant O-ring bore seals and axial port opening laterally into space between O-rings to enable testing of seals. Axial passage in plug connected through radial passage to space between O-rings. Opening used to test O-rings, then sealed with smaller O-ring compressed by machine screw. Useful to seal test or cleanout holes normally kept closed in hydraulic actuators, pumps, and other pressurized systems.

  9. Visible and infrared mapping spectrometer for exploration of comets, asteroids, and the Saturnian system of rings and moons

    NASA Technical Reports Server (NTRS)

    Juergens, David W.; Duval, James E.; Lockhart, Robert F.; Langevin, Yves; Formisano, Vittorio; Bellucci, Giancarlo

    1991-01-01

    Consideration is given to a visible and infrared mapping spectrometer (VIMS) developed by American, Italian, and French scientists and engineers as a facility instrument for the Comet Rendezvous Asteroid Flyby (CRAF) mission and as a candidate facility instrument for the Cassini mission to explore Saturn and its rings and moons. VIMS is characterized by 0.35-5.2 micron spectral range with a nominal spatial resolution of 0.5 mrad and spectral resolutions of 7 nm at 0.35-1.0 micron wavelength and 16 nm at 1.0-5.2 micron wavelength.

  10. New dust belts of Uranus: one ring, two ring, red ring, blue ring.

    PubMed

    de Pater, Imke; Hammel, Heidi B; Gibbard, Seran G; Showalter, Mark R

    2006-04-07

    We compared near-infrared observations of the recently discovered outer rings of Uranus with Hubble Space Telescope results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/2003 U 1 is probably produced by impacts into the embedded moon Mab, which apparently orbits at a location where nongravitational perturbations favor the survival and spreading of submicron-sized dust. R/2003 U 2 more closely resembles Saturn's G ring, which is red, a typical color for dusty rings.

  11. A summary of laboratory testing performed to characterize and select an elastomeric O-ring material to be used in the redesigned solid rocket motors of the space transportation system

    NASA Technical Reports Server (NTRS)

    Turner, J. E.

    1993-01-01

    An elastomeric O-ring material is used in the joints of the redesigned solid motors (RSRM's) of the National Space Transportation System (NSTS). The selection of the O-ring material used in the RSRM's was a very thorough process that included efforts by NASA's Marshall Space Flight Center and the Langley Research Center, and the Thiokol Corporation. One of the efforts performed at MSFC was an extensive in-house laboratory test regime to screen potential O-ring materials and ultimately to characterize the elastomeric material that was chosen to be used in the RSRM's. The laboratory tests performed at MSFC are summarized.

  12. Boom and Bust Cycles in Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Esposito, L. W.; Meinke, B. K.; Sremcevic, M.; Albers, N.

    2010-12-01

    Cassini UVIS occultation data show clumping in Saturn’s F ring and at the B ring outer edge, indicating aggregation and disaggregation at these locations perturbed by Mimas and Prometheus. Timescales range from hours to months. The maximum clumping lags the moon by roughly π in the forcing frame. This indicates a direct relation between the moon and the ring clumping. We propose that the collective behavior of the ring particles resembles a predator-prey system: the aggregate mean size is the prey, which feeds the velocity dispersion; conversely, increasing dispersion breaks up the aggregates. For realistic values of the parameters this creates a limit cycle behavior, as for the ecology of foxes and hares or the boom-bust economic cycle. Solving for the long-term behavior of this forced system gives a periodic response at the perturbing frequency, with a phase lag roughly consistent with the UVIS occultation measurements. We conclude that the agitation by the moons at both these locations in the F ring and at the B ring outer edge drives aggregation and disaggregation in the forcing frame. This agitation of the ring material allows fortuitous formation of solid objects from the temporary clumps, via stochastic processes like compaction, adhesion, sintering or reorganization that drives the denser parts of the aggregate to the center or ejects the lighter elements. These more persistent objects would then orbit at the Kepler rate. Such processes can create the equinox objects seen at the B ring edge and in the F ring, explain the ragged nature of those ring regions and allow for rare events to aggregate ring particles into solid objects, recycling the ring material and extending the ring lifetime.

  13. Boom and Bust Cycles in Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Esposito, Larry W.; Meinke, B. K.; Sremcevic, M.; Albers, N.

    2010-10-01

    7/16/10 12:23 PM UVIS occultation data show clumping in Saturn's F ring and at the B ring outer edge, indicating aggregation and disaggregation at these locations perturbed by Mimas and Prometheus. Timescales range from hours to months. The maximum clumping lags the moon by π in the forcing frame. This indicates a direct relation between the moon and the ring clumping. We propose that the collective behavior of the ring particles resembles a predator-prey system: the aggregate mean size is the prey, which feeds the velocity dispersion; conversely, increasing dispersion breaks up the aggregates. For realistic values of the parameters this creates a limit cycle behavior, as for the ecology of foxes and hares or the boom-bust economic cycle. Solving for the long-term behavior of this forced system gives a periodic response at the perturbing frequency, with a phase lag consistent with the UVIS occultation measurements. We conclude that the agitation by the moons at both these locations in the F ring and at the B ring outer edge drives aggregation and disaggregation in the forcing frame. This agitation of the ring material allows fortuitous formation of solid objects from the temporary clumps, via stochastic processes like compaction, adhesion, sintering or reorganization that drives the denser parts of the aggregate to the center or ejects the lighter elements. These more persistent objects would then orbit at the Kepler rate. Such processes can create the equinox objects seen at the B ring edge and in the F ring, explain the ragged nature of those ring regions and allow for rare events to aggregate ring particles into solid objects, recycling the ring material and extending the ring lifetime. 7/16/10 12:23 PM 7/16/10 12:23 PM

  14. Future studies of planetary rings by space probes

    NASA Technical Reports Server (NTRS)

    Stone, E. C.

    1984-01-01

    Recent space probe observations of the rings of Jupiter and Saturn have furnished a substantial enhancement of the current understanding of the outer planets' rings. Voyager 2 offers further opportunities for the study of the Neptune and Uranus ring systems. The Galileo mission to Jupiter furnishes the first opportunity for long term space probe studies of a planetary ring system. It is suggested that an appropriately instrumented Saturn orbiter would not only provide a similar opportunity for the study of the Saturn rings, but may also be the only means by which to adequately address the nature of the diverse phenomena displayed by this prototypical planetary ring system.

  15. Saturn's F-Ring

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This narrow-angle camera image of Saturn's F Ring was taken through the Clear filter while at a distance of 6.9 million km from Saturn on 8 November 1980. The brightness variations of this tightly-constrained ring shown here indicate that the ring is less uniform in makeup than the larger rings. JPL managed the Voyager Project for NASA's Office of Space Science

  16. Interactive Visualization of Shadow Effects in the Planetary System of Saturn, its Rings and its Moons using an OpenGL Shader in IDL

    NASA Astrophysics Data System (ADS)

    Fajardo Hernandez, E. M.; Pomarède, D.

    2012-09-01

    The planetary system of Saturn, its rings and its moons is a fantastic playground where physicists are confronting theories and observations. Since its insertion into orbit in 2004, the Cassini-Huygens spacecraft has returned a wealth of high-resolution images and data that calls for the development of dedicated interactive, immersive, three-dimensional, multi-purpose analysis and visualization tools. Alongside with observations, numerical simulations also provide new insights into the fundamental processes at stake in the formation of this system. The SDvision graphical interface, developed in the context of IDL Object Graphics and intended primarily for the visualization of complex and massive astrophysical plasma simulations, has been extended to provide an interactive visualization of both numerical simulations and observations of Saturn, its rings, and its moons. One major missing feature of IDL Object Graphics is the ability to render shadow effects at all. We have overcome this limitation by developing a custom GLSL Shader that is invoked by IDL objects. This Shader, based on purely geometrical computations, is fast and allows for seamless exploratory visualization of the planetary system.

  17. Storage ring injection

    SciTech Connect

    Burke, R.J.

    1980-01-01

    Some basic issues involved in injecting the beam into storage rings with the principal parameters of those studied at the workshop have been considered. The main conclusion is that straightforward adjustments of the storage ring parameters makes injection easy. The largest number of injected turns is fourteen, and the phase space dilution allowance seems adequate to ensure very small beam loss during injection. The adjustments also result in lower bending magnet fields, and high field superconducting magnets (e.g., 5 Tesla) are not necessary. The design changes do not necessarily affect the Keil-Schnell criterion for stability of the longitudinal microwave instability, although that criterion appears to be irrelevant. Because the beams are expected to be unstable, but with slow growth rates, the vacuum chamber impedances required to give equal risetimes for the various designs are compared for systems posing various degrees of difficulty for injection. Finally, the impact of the parameters on cost is noted, and a system is considered that cuts the length of the linac in half by using doubly charged ions.

  18. The ultrastructure of the anterior end of male Onchocerca volvulus: papillae, amphids, nerve ring and first indication of an excretory system in the adult filarial worm.

    PubMed

    Strote, G; Bonow, I; Attah, S

    1996-07-01

    A detailed morphological investigation of the anterior sensory organs, the nerve ring and a glomerulus-like structure in male Onchocerca volvulus was performed by means of electron microscopy. The 8 head papillae are arranged in the common 4 + 4 pattern of most filarial worms in circles around the mouth opening. The amphidial openings are found between the circles of inner and outer papillae on both sides of the mouth. Inside, several additional nerve axons are seen in the tissue of the anterior tip not related to one of the identified papillar structures. The inner and outer papillae exhibit a remarkably different fine structure, and are part of a complex system of at least 2 different receptor cell types at the anterior tip of the worm. The amphidial channel contains 8 modified cilia; accessory axons are associated with the cytoplasm of the sheath cell. The anterior nerve ring of male worms is located about 150 micrometers posterior from the outermost tip of the head region. It consists of several fibres coiled around the oesophagus. The comparison of the fine structure of the central nervous system did not show the expected morphological differences associated with the heterogeneous age distribution in the natural worm population. This was in contrast to previous findings with respect to tissues in different parts of the worm. The study also provides the first evidence that suggests the existence of an excretory organ in a filarial worm in the region of the anterior nerve ring. Paired glomerulus-like structures in the lateral chords and a canal formed by a projection of the basal zone of the cuticles were identified.

  19. On certain Hecke rings

    PubMed Central

    Evens, Sam; Bressler, Paul

    1987-01-01

    We examine rings that embed into the smash product of the group algebra of the Weyl group with the field of meromorphic functions on the Cartan subalgebra and are generated by elements that satisfy braid relations. We prove that every such ring is isomorphic to either the Hecke algebra, the nil Hecke ring, or the group algebra of the Weyl group. PMID:16593804

  20. The Jumping Ring Experiment

    ERIC Educational Resources Information Center

    Baylie, M.; Ford, P. J.; Mathlin, G. P.; Palmer, C.

    2009-01-01

    The jumping ring experiment has become central to liquid nitrogen shows given as part of the outreach and open day activities carried out within the University of Bath. The basic principles of the experiment are described as well as the effect of changing the geometry of the rings and their metallurgical state. In general, aluminium rings are…

  1. Rings Around Uranus

    ERIC Educational Resources Information Center

    Maran, Stephen P.

    1977-01-01

    Events leading up to the discovery of the rings of Uranus are described. The methods used and the logic behind the methods are explained. Data collected to prove the existence of the rings are outlined and theories concerning the presence of planetary rings are presented. (AJ)

  2. Soft normed rings.

    PubMed

    Uluçay, Vakkas; Şahin, Mehmet; Olgun, Necati

    2016-01-01

    Molodtsov introduced the concept of soft sets, which can be seen as a new mathematical tool for dealing with uncertainty. In this paper, we initiate the study of soft normed rings by soft set theory. The notions of soft normed rings, soft normed ideals, soft complete normed rings are introduced and also several related properties and examples are given.

  3. On the vortex ring state

    NASA Astrophysics Data System (ADS)

    Green, Richard; Gillies, E.; Giuni, M.; Hislop, J.; Savas, Omer

    2014-11-01

    The investigation considers the vortex ring state, a phenomenon normally associated with the collapse of a trailing, helical vortex wake into a unstable vortex ring, and is a problem encountered when a helicopter rotor descends into its own wake. A series of wind tunnel and towing tank experiments on rotor systems have been performed, and a comparison is then made with the behaviour of a specially designed open core, annular jet system that generates a mean flow velocity profile similar to that observed below a rotor. In experimentally simulated descents the jet system forms flow patterns that are topologically similar to the vortex ring state of a rotor system. Furthermore the dynamic behaviour of the flow shares many of the important characteristics of the rotor flow. This result suggests that the phenomenon of the vortex ring state of a rotor wake is decoupled from the detailed vortex dynamics of the helical vortex filaments themselves. The presentation will describe the principle behind the investigation, the details of the annular jet system and the results gained using PIV and flow visualisation of the wake and jet systems.

  4. Archiving of Planetary Ring Data

    NASA Technical Reports Server (NTRS)

    Elliot, James L.

    2001-01-01

    Stellar occultation data provide our only Earth-based means of probing planetary rings at kilometer spatial resolution. The occultation data archive at MIT contains original data and analysis products of stellar occultations by the ring systems of the planets Jupiter, Saturn, Uranus, and Neptune observed by members of the group (and other groups) from 1977 to the present. During this time period, several media have been used to record and store the original and processed data: (1) chart records; (2) printed output, (3) audio reel tape; (4) audio cassette tape; (5) 7-track, 1/2-inch computer tape; (6) 9-track, 1/2-inch computer tape at 800, 1600, and 6250 bpi; (7) NOVA disk platters (2.5 and 5.0 Mbyte); (8) write once optical disks; (9) punched cards; and (10) read-write optical disks. With the rapid change of computer technology over this time period, some of these media have become not only obsolete, but nearly extinct. In particular, it has become nearly impossible to find any facilities that can still read 800 bpi tapes, which contain the only copies of several important data sets for the ring system of Uranus. In particular, we have an extensive ring data collection that includes data sets for the following Uranian ring occultations: U0, U11, U12, U13, U14, U25, U17, and U36.

  5. Hydrodynamic Simulations of Planetary Rings

    NASA Astrophysics Data System (ADS)

    Miller, Jacob; Stewart, G. R.; Esposito, L. W.

    2013-10-01

    Simulations of rings have traditionally been done using N-body methods, granting insight into the interactions of individual ring particles on varying scales. However, due to the scale of a typical ring system and the sheer number of particles involved, a global N-body simulation is too computationally expensive, unless particle collisions are replaced by stochastic forces (Bromley & Kenyon, 2013). Rings are extraordinarily flat systems and therefore are well-suited to existing geophysical shallow-water hydrodynamics models with well-established non-linear advection methods. By adopting a general relationship between pressure and surface density such as a polytropic equation of state, we can modify the shallow-water formula to treat a thin, compressible, self-gravitating, shearing fluid. Previous hydrodynamic simulations of planetary rings have been restricted to axisymmetric flows and therefore have not treated the response to nonaxisymmetric perturbations by moons (Schmidt & Tscharnuter 1999, Latter & Ogilvie 2010). We seek to expand on existing hydrodynamic methods and, by comparing our work with complementary N-body simulations and Cassini observations, confirm the veracity of our results at small scales before eventually moving to a global domain size. We will use non-Newtonian, dynamically variable viscosity to model the viscous transport caused by unresolved self-gravity wakes. Self-gravity will be added to model the dynamics of large-scale structures, such as density waves and edge waves. Support from NASA Outer Planets and Planetary Geology and Geophysics programs is gratefully acknowledged.

  6. Dynamics of dust in Jupiter's gossamer rings

    NASA Astrophysics Data System (ADS)

    Hamilton, D.; Burns, J.; Krueger, H.; Showalter, M.

    2003-04-01

    Over the past several years, the Galileo spacecraft has drastically improved our knowledge of Jupiter's faint rings. We now know the system to be composed of a main ring 7000km wide whose inner edge blossoms into a vertically-extended halo, and a pair of gossamer rings, each one extending inward from a small moon. These moonlets, Thebe and Amalthea, have large orbital tilts and resulting vertical excursions of 1150km and 4300km, respectively. The vertical thicknesses of the two Gossamer rings accurately match these values, providing compelling evidence that the two small satellites act as the dominant sources of ring material. Ring Material is born during high speed impacts onto the moonlet surfaces, after which the material evolves inward under the action of a dissipative force, either Poynting-Robertson Drag or Resonant Charge Variations. The basic framework for the origin and evolution of the Gossamer Rings is well understood, but there are a few loose ends that are not so easily explained: i) an outward extension of the Thebe Ring, ii) the nature of the dissipative force. In this talk I will report my latest dynamical modeling of the Gossamer rings associated with Thebe and Amalthea, and will discuss how in-situ impact data collected by the Galileo dust detector during the first ever ring "fly-through" may help to resolve some of these and other outstanding issues.

  7. 5,10b-Ethanophenanthridine amaryllidaceae alkaloids inspire the discovery of novel bicyclic ring systems with activity against drug resistant cancer cells.

    PubMed

    Henry, Sean; Kidner, Ria; Reisenauer, Mary R; Magedov, Igor V; Kiss, Robert; Mathieu, Véronique; Lefranc, Florence; Dasari, Ramesh; Evidente, Antonio; Yu, Xiaojie; Ma, Xiuye; Pertsemlidis, Alexander; Cencic, Regina; Pelletier, Jerry; Cavazos, David A; Brenner, Andrew J; Aksenov, Alexander V; Rogelj, Snezna; Kornienko, Alexander; Frolova, Liliya V

    2016-09-14

    Plants of the Amaryllidaceae family produce a large variety of alkaloids and non-basic secondary metabolites, many of which are investigated for their promising anticancer activities. Of these, crinine-type alkaloids based on the 5,10b-ethanophenanthridine ring system were recently shown to be effective at inhibiting proliferation of cancer cells resistant to various pro-apoptotic stimuli and representing tumors with dismal prognoses refractory to current chemotherapy, such as glioma, melanoma, non-small-cell lung, esophageal, head and neck cancers, among others. Using this discovery as a starting point and taking advantage of a concise biomimetic route to the crinine skeleton, a collection of crinine analogues were synthetically prepared and evaluated against cancer cells. The compounds exhibited single-digit micromolar activities and retained this activity in a variety of drug-resistant cancer cell cultures. This investigation resulted in the discovery of new bicyclic ring systems with significant potential in the development of effective clinical cancer drugs capable of overcoming cancer chemotherapy resistance.

  8. Simulation of Rings about Ellipsoidal Bodies

    NASA Astrophysics Data System (ADS)

    Gupta, Akash; Nadkarni-Ghosh, Sharvari; Sharma, Ishan

    2016-10-01

    Recent discovery of rings around Chariklo, a centaur orbiting the Sun (F. Braga-Ribas et al., 2014) and speculations of rings around minor planet, Chiron (Ortiz et al., 2015), Saturn's satellites, Rhea (Jones et al., 2008; Schenk et al., 2011), Iapetus (Ip, 2006) or exoplanets, suggest that rings about non-spherical bodies is perhaps a more general phenomenon than anticipated. As a first step towards understanding such systems, we examine the dynamical behavior of rings around similar bodies using N-body simulations. Our code employs the `local simulation method' (Wisdom & Tremaine, 1988; Salo, 1995) and accounts for particle interactions via collisions using Discrete Element Method (Cundall & Strack, 1978; Bhateja et al., 2016) and mutual gravitation. The central body has been modeled as an axisymmetric ellipsoid characterized by its axis ratio, or defined via characteristic frequencies (circular, vertical and epicyclic frequency) representing the gravitational field of an axisymmetric body. We vary the central body's characterizing parameter and observe the change in various ring properties like the granular temperature, impact frequency, radial width and vertical thickness. We also look into the effect on ring properties upon variation in the size of the central body-ring system. Further, we investigate the role of characteristic frequencies in dictating the ring dynamics, and how this could help in qualitatively estimating the ring dynamics about any arbitrary central body with symmetry about the equatorial plane and the axis normal to it.

  9. On the solar dust ring(s)

    NASA Astrophysics Data System (ADS)

    Mukai, T.

    Based on a mechanism to form the solar dust ring, it is proved that the observed peak in infrared F-corona cannot be explained by silicate type grains alone. Preliminary analysis on the recent infrared data of the F-corona by Maihara et al. (1984) has suggested that the ring particles have different physical properties compared with the dust grains, which produce the background F-corona.

  10. Accretion in Saturn's F Ring

    NASA Astrophysics Data System (ADS)

    Meinke, B. K.; Esposito, L. W.; Stewart, G.

    2012-12-01

    Saturn's F ring is the solar system's principal natural laboratory for direct observation of accretion and disruption processes. The ring resides in the Roche zone, where tidal disruption competes with self-gravity, which allows us to observe the lifecycle of moonlets. Just as nearby moons create structure at the B ring edge (Esposito et al. 2012) and the Keeler gap (Murray 2007), the F ring "shepherding" moons Prometheus and Pandora stir up ring material and create observably changing structures on timescales of days to decades. In fact, Beurle et al (2010) show that Prometheus makes it possible for "distended, yet gravitationally coherent clumps" to form in the F ring, and Barbara and Esposito (2002) predicted a population of ~1 km bodies in the ring. In addition to the observations over the last three decades, the Cassini Ultraviolet Imaging Spectrograph (UVIS) has detected 27 statistically significant features in 101 occultations by Saturn's F ring since July 2004. Seventeen of those 27 features are associated with clumps of ring material. Two features are opaque in occultation, which makes them candidates for solid objects, which we refer to as Moonlets. The 15 other features partially block stellar signal for 22 m to just over 3.7 km along the radial expanse of the occultation. Upon visual inspection of the occultation profile, these features resemble Icicles, thus we will refer to them as such here. The density enhancements responsible for such signal attenuations are likely due to transient clumping of material, evidence that aggregations of material are ubiquitous in the F ring. Our lengthy observing campaign reveals that Icicles are likely transient clumps, while Moonlets are possible solid objects. Optical depth is an indicator of clumping because more-densely aggregated material blocks more light; therefore, it is natural to imagine moonlets as later evolutionary stage of icicle, when looser clumps of material compact to form a feature that appears

  11. Traversable wormholes: The Roman ring

    SciTech Connect

    Visser, M.

    1997-04-01

    In this Brief Report I introduce yet another class of geometries for which semiclassical chronology protection theorems are of dubious physical reliability. I consider a {ital {open_quotes}Roman ring{close_quotes}} of traversable wormholes, wherein a number of wormholes are arranged in a ring in such a manner that no subset of wormholes is near chronology violation, though the combined system can be arbitrarily close to chronology violation. I show that (with enough wormholes in the ring) the gravitational vacuum polarization (the expectation value of the quantum stress-energy tensor) can be made arbitrarily small. In particular, the back reaction can be kept arbitrarily small all the way to the {open_quotes}reliability horizon,{close_quotes} so that semiclassical quantum gravity becomes unreliable before the gravitational back reaction becomes large. {copyright} {ital 1997} {ital The American Physical Society}

  12. Let Freedom Ring! Bulletin, 1937, No. 32

    ERIC Educational Resources Information Center

    Calhoun, Harold G.; Calhoun, Dorothy; Hatch, Roy W.; Cohen, Philip H.; Schramm, Rudolf

    1937-01-01

    This volume of "Let Freedom Ring!" contains the scripts of the 13 national broadcasts of the radio series of that name presented in the spring of 1937 over the national network of the Columbia Broadcast System. In "Let Freedom Ring!" you will find the courage, the struggle, the triumph of men and women who fought to win and safeguard liberties…

  13. Storage ring development at the National Synchrotron Light Source

    SciTech Connect

    Krinsky, S.; Bittner, J.; Fauchet, A.M.; Johnson, E.D.; Keane, J.; Murphy, J.; Nawrocky, R.J.; Rogers, J.; Singh, O.V.; Yu, L.H.

    1991-09-01

    This report contains papers on the following topics: Transverse Beam Profile Monitor; Bunch Length Measurements in the VUV Storage Ring; Photoelectric Effect Photon Beam Position Monitors; RF Receivers for Processing Electron Beam Pick-up Electrode Signals; Real-Time Global Orbit Feedback Systems; Local Orbit Feedback; Active Interlock System for High Power Insertion Devices in the X-ray Ring; Bunch Lengthening Cavity for the VUV Ring; SXLS Storage Ring Design.

  14. Slowing of Vortex Rings

    NASA Astrophysics Data System (ADS)

    Donnelly, Russell; Bolster, Diogo; Hershberger, Robert

    2008-11-01

    We have investigated the slowing of vortex rings in water which are created with very thin cores. We find that these rings propagate with no measurable change in diameter or core size. The drag appears to be the result of viscous forces on the core. A simple model for this drag describes experimental data in terms of a drag coefficient, which depends only on Reynolds number. Barenghi's group at Newcastle found that the translational velocity of a ring in an inviscid fluid perturbed by Kelvin waves decreases with increasing amplitude of Kelvin waves. This suggests that the velocity of vortex rings in a viscous fluid may well depend on the amplitude of Kelvin waves at the time of formation. Rings with substantial amplitude of Kelvin waves will be expected to move more slowly than rings with little or no Kelvin wave amplitude. We present experimental data confirming this suggestion.

  15. A topologically driven glass in ring polymers

    PubMed Central

    Michieletto, Davide; Turner, Matthew S.

    2016-01-01

    The static and dynamic properties of ring polymers in concentrated solutions remains one of the last deep unsolved questions in polymer physics. At the same time, the nature of the glass transition in polymeric systems is also not well understood. In this work, we study a novel glass transition in systems made of circular polymers by exploiting the topological constraints that are conjectured to populate concentrated solutions of rings. We show that such rings strongly interpenetrate through one another, generating an extensive network of topological interactions that dramatically affects their dynamics. We show that a kinetically arrested state can be induced by randomly pinning a small fraction of the rings. This occurs well above the classical glass transition temperature at which microscopic mobility is lost. Our work both demonstrates the existence of long-lived inter-ring penetrations and realizes a novel, topologically induced, glass transition. PMID:27118847

  16. Pleiotropic and epistatic behavior of a ring-hydroxylating oxygenase system in the polycyclic aromatic hydrocarbon metabolic network from Mycobacterium vanbaalenii PYR-1.

    PubMed

    Kweon, Ohgew; Kim, Seong-Jae; Kim, Dae-Wi; Kim, Jeong Myeong; Kim, Hyun-lee; Ahn, Youngbeom; Sutherland, John B; Cerniglia, Carl E

    2014-10-01

    Despite the considerable knowledge of bacterial high-molecular-weight (HMW) polycyclic aromatic hydrocarbon (PAH) metabolism, the key enzyme(s) and its pleiotropic and epistatic behavior(s) responsible for low-molecular-weight (LMW) PAHs in HMW PAH-metabolic networks remain poorly understood. In this study, a phenotype-based strategy, coupled with a spray plate method, selected a Mycobacterium vanbaalenii PYR-1 mutant (6G11) that degrades HMW PAHs but not LMW PAHs. Sequence analysis determined that the mutant was defective in pdoA2, encoding an aromatic ring-hydroxylating oxygenase (RHO). A series of metabolic comparisons using high-performance liquid chromatography (HPLC) analysis revealed that the mutant had a lower rate of degradation of fluorene, anthracene, and pyrene. Unlike the wild type, the mutant did not produce a color change in culture media containing fluorene, phenanthrene, and fluoranthene. An Escherichia coli expression experiment confirmed the ability of the Pdo system to oxidize biphenyl, the LMW PAHs naphthalene, phenanthrene, anthracene, and fluorene, and the HMW PAHs pyrene, fluoranthene, and benzo[a]pyrene, with the highest enzymatic activity directed toward three-ring PAHs. Structure analysis and PAH substrate docking simulations of the Pdo substrate-binding pocket rationalized the experimentally observed metabolic versatility on a molecular scale. Using information obtained in this study and from previous work, we constructed an RHO-centric functional map, allowing pleiotropic and epistatic enzymatic explanation of PAH metabolism. Taking the findings together, the Pdo system is an RHO system with the pleiotropic responsibility of LMW PAH-centric hydroxylation, and its epistatic functional contribution is also crucial for the metabolic quality and quantity of the PAH-MN.

  17. Pleiotropic and Epistatic Behavior of a Ring-Hydroxylating Oxygenase System in the Polycyclic Aromatic Hydrocarbon Metabolic Network from Mycobacterium vanbaalenii PYR-1

    PubMed Central

    Kweon, Ohgew; Kim, Seong-Jae; Kim, Dae-Wi; Kim, Jeong Myeong; Kim, Hyun-lee; Ahn, Youngbeom; Sutherland, John B.

    2014-01-01

    Despite the considerable knowledge of bacterial high-molecular-weight (HMW) polycyclic aromatic hydrocarbon (PAH) metabolism, the key enzyme(s) and its pleiotropic and epistatic behavior(s) responsible for low-molecular-weight (LMW) PAHs in HMW PAH-metabolic networks remain poorly understood. In this study, a phenotype-based strategy, coupled with a spray plate method, selected a Mycobacterium vanbaalenii PYR-1 mutant (6G11) that degrades HMW PAHs but not LMW PAHs. Sequence analysis determined that the mutant was defective in pdoA2, encoding an aromatic ring-hydroxylating oxygenase (RHO). A series of metabolic comparisons using high-performance liquid chromatography (HPLC) analysis revealed that the mutant had a lower rate of degradation of fluorene, anthracene, and pyrene. Unlike the wild type, the mutant did not produce a color change in culture media containing fluorene, phenanthrene, and fluoranthene. An Escherichia coli expression experiment confirmed the ability of the Pdo system to oxidize biphenyl, the LMW PAHs naphthalene, phenanthrene, anthracene, and fluorene, and the HMW PAHs pyrene, fluoranthene, and benzo[a]pyrene, with the highest enzymatic activity directed toward three-ring PAHs. Structure analysis and PAH substrate docking simulations of the Pdo substrate-binding pocket rationalized the experimentally observed metabolic versatility on a molecular scale. Using information obtained in this study and from previous work, we constructed an RHO-centric functional map, allowing pleiotropic and epistatic enzymatic explanation of PAH metabolism. Taking the findings together, the Pdo system is an RHO system with the pleiotropic responsibility of LMW PAH-centric hydroxylation, and its epistatic functional contribution is also crucial for the metabolic quality and quantity of the PAH-MN. PMID:25070740

  18. Radioactive gold ring dermatitis

    SciTech Connect

    Miller, R.A.; Aldrich, J.E. )

    1990-08-01

    A superficial squamous cell carcinoma developed in a woman who wore a radioactive gold ring for more than 30 years. Only part of the ring was radioactive. Radiation dose measurements indicated that the dose to basal skin layer was 2.4 Gy (240 rad) per week. If it is assumed that the woman continually wore her wedding ring for 37 years since purchase, she would have received a maximum dose of approximately 4600 Gy.

  19. Saturn's E ring revisited

    NASA Astrophysics Data System (ADS)

    Feibelman, W. A.; Klinglesmith, D. A.

    1980-07-01

    Images of the E ring of Saturn obtained by the image processing of photographs of the 1966 edge-on presentation of the planet's ring plane are presented. Two methods of image enhancement were used: scanning with an image quantizer operated in the derivative mode to enhance contrast and computerized subtraction of a circularly symmetric image of the overexposed Saturn disk. Further photographic and CCD observation confirming the existence of the ring extending to twice the diameter of the A ring, which was not detected by the Pioneer 11 imaging photopolarimeter, is indicated.

  20. Electro-optical hybrid slip ring

    NASA Astrophysics Data System (ADS)

    Hong, En

    2005-11-01

    The slip ring is a rotary electrical interface, collector, swivel or rotary joint. It is a physical system that can perform continuous data transfer and data exchange between a stationary and a rotating structure. A slip ring is generally used to transfer data or power from an unrestrained, continuously rotating electro-mechanical system in real-time, thereby simplifying operations and eliminating damage-prone wires dangling from moving joints. Slip rings are widely used for testing, evaluating, developing and improving various technical equipment and facilities with rotating parts. They are widely used in industry, especially in manufacturing industries employing turbo machinery, as in aviation, shipbuilding, aerospace, defense, and in precise facilities having rotating parts such as medical Computerized Tomography (CT) and MRI scanners and so forth. Therefore, any improvement in slip ring technology can impact large markets. Research and development in this field will have broad prospects long into the future. The goal in developing the current slip ring technology is to improve and increase the reliability, stability, anti-interference, and high data fidelity between rotating and stationary structures. Up to now, there have been numerous approaches used for signal and data transfer utilizing a slip ring such as metal contacts, wires, radio transmission, and even liquid media. However, all suffer from drawbacks such as data transfer speed limitations, reliability, stability, electro-magnetic interference and durability. The purpose of the current research is to break through these basic limitations using an optical solution, thereby improving performance in current slip ring applications. This dissertation introduces a novel Electro-Optical Hybrid Slip Ring technology, which makes "through the air" digital-optical communication between stationary and rotating systems a reality with high data transfer speed, better reliability and low interference susceptibility

  1. Edge-on View of Saturn's Rings

    NASA Technical Reports Server (NTRS)

    1996-01-01

    TOP - This is a NASA Hubble Space Telescope snapshot of Saturn with its rings barely visible. Normally, astronomers see Saturn with its rings tilted. Earth was almost in the plane of Saturn's rings, thus the rings appear edge-on.

    In this view, Saturn's largest moon, Titan, is casting a shadow on Saturn. Titan's atmosphere is a dark brown haze. The other moons appear white because of their bright, icy surfaces. Four moons - from left to right, Mimas, Tethys, Janus, and Enceladus - are clustered around the edge of Saturn's rings on the right. Two other moons appear in front of the ring plane. Prometheus is on the right edge; Pandora, on the left. The rings also are casting a shadow on Saturn because the Sun was above the ring plane.

    BOTTOM - This photograph shows Saturn with its rings slightly tilted. The moon called Dione, on the lower right, is casting a long, thin shadow across the whole ring system due to the setting Sun on the ring plane. The moon on the upper left of Saturn is Tethys.

    Astronomers also are studying the unusual appearance of Saturn's rings. The bottom image displays a faint, narrow ring, the F-ring just outside the main ring, which normally is invisible from Earth. Close to the edge of Saturn's disk, the front section of rings seem brighter and more yellow than the back due to the additional lumination by yellowish Saturn.

    The color images were assembled from separate exposures taken August 6 (top) and November 17 (bottom), 1995 with the Wide Field Planetary Camera-2.

    The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.

    This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

  2. The origin and evolution of the Uranian dust rings

    SciTech Connect

    Colwell, J.E.

    1989-01-01

    The numerous dust bands discovered by Voyager 2 at Uranus have lifetimes on the order of 100 years against orbital decay by exospheric drag. A system of low optical depth rings of 10 meter to 1 km sized bodies (moonlet belts) are proposed as continuing sources of the dust particles. The ring system is modeled as a Markov Chain consisting of states through which dust particle evolve with time. Physical processes included in the model are orbit decay by exospheric drag and Poynting-Robertson light drag; destruction of grains by meteoroid impact; transport of dust through the classical rings and moonlet belts; creation of dust particles from meteoroid impacts onto rings, moons, and moonlet belts; liberation of regolith material through ring and moonlet belt particle collisions; and sweepup of ejecta by ring and moonlet belt particles. The optical depth profiles for the main rings from Voyager 2 Photopolarimeter Subsystem (PPS) occultation observation are used in modeling the transport of dust through the rings. Simulations of the Uranus ring system show that this model reproduces the observed characteristics of the Uranus dust rings. The moonlet belt model is applied to the rings of Jupiter, Saturn, and Neptune, and is capable of reproducing some of the observed characteristics of those ring systems. The moonlet belt objects fit on a collisionally derived power-law size distribution with the other components of the ring moon systems. Since the rings and moonlet belts have lifetimes due to viscous spreading less than the age of the solar system, a net model of planetary rings emerges in which the rings are continually created from the disruption of small satellites by meteoroid bombardment.

  3. Modified spiral wound retaining ring

    NASA Technical Reports Server (NTRS)

    Lawson, A. G. (Inventor)

    1980-01-01

    A spiral wound retaining ring with angled ends is described. The ring is crimped at the same angle as the ring ends to maintain a constant thickness dimension. The angling of the ends of the ring and crimp allow the ends to be positioned closer together while maintaining enough clearance to enable insertion and removal of the ring. By reducing the separation distance between the ends a stronger ring results since the double layer area of the ring is maximized.

  4. A DFT investigation of base-catalyzed β-elimination reactions in water solution for systems activated by the pyridine ring: Theory vs. experiment

    NASA Astrophysics Data System (ADS)

    Mosconi, Edoardo; De Angelis, Filippo; Tarantelli, Francesco; Alunni, Sergio; Sgamellotti, Antonio

    2008-07-01

    We report a theoretical investigation of β-elimination reactions in systems activated by the pyridine ring. The investigated reaction, the acetohydroxamate-induced β-elimination in protonated N-[2-(2-pyridyl)ethyl]quinuclidinium, offers a unique opportunity to test computational methodologies since detailed kinetic experimental data are available. We calculated the p Kas of the acetohydroxamic acid and the substrate and thoroughly characterized the reactive free-energy profile. The reaction proceeds via a stable carbanion intermediate. Except a discrepancy in the reproduction of the p Ka of the acetohydroxamic acid, the calculated free-energy profile is in excellent agreement with the experiment, showing the general reliability of the present approach.

  5. Technique distribuee de gestion de la charge sur le reseau electrique et ring-tree: Un nouveau systeme de communication P2P

    NASA Astrophysics Data System (ADS)

    Ayoub, Simon

    Le reseau de distribution et de transport de l'electricite se modernise dans plusieurs pays dont le Canada. La nouvelle generation de ce reseau que l'on appelle smart grid, permet entre autre l'automatisation de la production, de la distribution et de la gestion de la charge chez les clients. D'un autre cote, des appareils domestiques intelligents munis d'une interface de communication pour des applications du smart grid commencent a apparaitre sur le marche. Ces appareils intelligents pourraient creer une communaute virtuelle pour optimiser leurs consommations d'une facon distribuee. La gestion distribuee de ces charges intelligentes necessite la communication entre un grand nombre d'equipements electriques. Ceci represente un defi important a relever surtout si on ne veut pas augmenter le cout de l'infrastructure et de la maintenance. Lors de cette these deux systemes distincts ont ete concus : un systeme de communication peer-to-peer, appele Ring-Tree, permettant la communication entre un nombre important de noeuds (jusqu'a de l'ordre de grandeur du million) tel que des appareils electriques communicants et une technique distribuee de gestion de la charge sur le reseau electrique. Le systeme de communication Ring-Tree inclut une nouvelle topologie reseau qui n'a jamais ete definie ou exploitee auparavant. Il inclut egalement des algorithmes pour la creation, l'exploitation et la maintenance de ce reseau. Il est suffisamment simple pour etre mis en oeuvre sur des controleurs associes aux dispositifs tels que des chauffe-eaux, chauffage a accumulation, bornes de recharges electriques, etc. Il n'utilise pas un serveur centralise (ou tres peu, seulement lorsqu'un noeud veut rejoindre le reseau). Il offre une solution distribuee qui peut etre mise en oeuvre sans deploiement d'une infrastructure autre que les controleurs sur les dispositifs vises. Finalement, un temps de reponse de quelques secondes pour atteindre 1'ensemble du reseau peut etre obtenu, ce qui est

  6. Comparative gene expression analysis among vocal learners (bengalese finch and budgerigar) and non-learners (quail and ring dove) reveals variable cadherin expressions in the vocal system.

    PubMed

    Matsunaga, Eiji; Okanoya, Kazuo

    2011-01-01

    Birds use various vocalizations to communicate with one another, and some are acquired through learning. So far, three families of birds (songbirds, parrots, and hummingbirds) have been identified as having vocal learning ability. Previously, we found that cadherins, a large family of cell-adhesion molecules, show vocal control-area-related expression in a songbird, the Bengalese finch. To investigate the molecular basis of evolution in avian species, we conducted comparative analysis of cadherin expressions in the vocal and other neural systems among vocal learners (Bengalese finch and budgerigar) and a non-learner (quail and ring dove). The gene expression analysis revealed that cadherin expressions were more variable in vocal and auditory areas compared to vocally unrelated areas such as the visual areas among these species. Thus, it appears that such diverse cadherin expressions might have been related to generating species diversity in vocal behavior during the evolution of avian vocal learning.

  7. Photochemistry of 1,4-Dihydropyridine Derivatives: Diradical Formation, Delocalization and Trapping as a Route to Novel Tricyclic and Tetracyclic Nitrogen Heterocyclic Ring Systems.

    PubMed

    Al-Jalal, Nader A; Ibrahim, Yehia A; Al-Awadi, Nouria A; Ibrahim, Maher R; Sayed, Osama M

    2016-06-30

    Irradiation of an acetonitrile solution of 4-aryl-3,5-dibenzoyl-1,4-dihydropyridine derivatives 1a-c and maleimides 2a-c using medium pressure Hg-arc lamp (λ > 290) nm afforded three different cycloadducts 4, 5, 6 in addition to the oxidation products 3. These results indicate that compounds 1a-c undergoes intermolecular cycloaddition reaction through three biradical intermediates and behave photochemically different than those reported previously for the analogous 3,5-diacetyl and 3,5-dicarboxylic acid derivatives. The present work also offers simple access to novel tricyclic and tetracyclic nitrogen heterocyclic ring systems of potential biological and synthetic applications. The structure of the photoproducts was established spectroscopically and by single crystal X-ray crystallography.

  8. Ring Buffered Network Bus

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This report describes the research effort to demonstrate the integration of a data sharing technology, Ring Buffered Network Bus, in development by Dryden Flight Research Center, with an engine simulation application, the Java Gas Turbine Simulator, in development at the University of Toledo under a grant from the Glenn Research Center. The objective of this task was to examine the application of the RBNB technologies as a key component in the data sharing, health monitoring and system wide modeling elements of the NASA Aviation Safety Program (AVSP) [Golding, 1997]. System-wide monitoring and modeling of aircraft and air safety systems will require access to all data sources which are relative factors when monitoring or modeling the national airspace such as radar, weather, aircraft performance, engine performance, schedule and planning, airport configuration, flight operations, etc. The data sharing portion of the overall AVSP program is responsible for providing the hardware and software architecture to access and distribute data, including real-time flight operations data, among all of the AVSP elements. The integration of an engine code capable of numerically "flying" through recorded flight paths and weather data using a software tool that allows for distributed access of data to this engine code demonstrates initial steps toward building a system capable of monitoring and modeling the National Airspace.

  9. Synthesis of prostanoids with bicyclo[2.2.1]heptane, bicyclo[3.1.1]heptane, and bicyclo[2.2.2]octane ring systems. Activities of 15-hydroxy epimers on human platelets.

    PubMed

    Wilson, N H; Peesapati, V; Jones, R L; Hamilton, K

    1982-05-01

    A number of prostanoids with bicyclo[2.2.1]heptane, bicyclo[3.1.1]heptane, and bicyclo[2.2.2]octane ring systems have been prepared by routes which allow the introduction of the omega chain after the alpha chain. The introduction of a 16-p-halophenoxy substituent confers platelet aggregation activity on both 15 alpha- and 15 beta-hydroxy epimers. In the case of the pinane thromboxane ring system, the natural omega-chain compound is an inhibitor of aggregation, whereas the 16-p-fluorophenoxy analogue is a potent aggregation agent.

  10. Slowing down of ring polymer diffusion caused by inter-ring threading.

    PubMed

    Lee, Eunsang; Kim, Soree; Jung, YounJoon

    2015-06-01

    Diffusion of long ring polymers in a melt is much slower than the reorganization of their internal structures. While direct evidence for entanglements has not been observed in the long ring polymers unlike linear polymer melts, threading between the rings is suspected to be the main reason for slowing down of ring polymer diffusion. It is, however, difficult to define the threading configuration between two rings because the rings have no chain end. In this work, evidence for threading dynamics of ring polymers is presented by using molecular dynamics simulation and applying a novel analysis method. The simulation results are analyzed in terms of the statistics of persistence and exchange times that have proved useful in studying heterogeneous dynamics of glassy systems. It is found that the threading time of ring polymer melts increases more rapidly with the degree of polymerization than that of linear polymer melts. This indicates that threaded ring polymers cannot diffuse until an unthreading event occurs, which results in the slowing down of ring polymer diffusion.

  11. Contactless Magnetic Slip Ring

    NASA Technical Reports Server (NTRS)

    Kumagai, Hiroyuki (Inventor); Deardon, Joe D. (Inventor)

    1997-01-01

    A contactless magnetic slip ring is disclosed having a primary coil and a secondary coil. The primary and secondary coils are preferably magnetically coupled together, in a highly reliable efficient manner, by a magnetic layered core. One of the secondary and primary coils is rotatable and the contactless magnetic slip ring provides a substantially constant output.

  12. Illustration of Saturn's Rings

    NASA Technical Reports Server (NTRS)

    2001-01-01

    This illustration shows a close-up of Saturn's rings. These rings are thought to have formed from material that was unable to form into a Moon because of tidal forces from Saturn, or from a Moon that was broken up by Saturn's tidal forces.

  13. Birth Control Ring

    MedlinePlus

    ... It? The birth control ring is a soft, flexible, doughnut-shaped ring about 2 inches (5 centimeters) in diameter. It is inserted into the vagina, where it slowly releases hormones — the chemicals the body makes to control organ function — through the vaginal wall into the ...

  14. Steroidal contraceptive vaginal rings.

    PubMed

    Sarkar, N N

    2003-06-01

    The development of steroid-releasing vaginal rings over the past three decades is reviewed to illustrate the role of this device as an effective hormonal contraceptive for women. Vaginal rings are made of polysiloxane rubber or ethylene-vinyl-acetate copolymer with an outer diameter of 54-60 mm and a cross-sectional diameter of 4-9.5 mm and contain progestogen only or a combination of progestogen and oestrogen. The soft flexible combined ring is inserted in the vagina for three weeks and removed for seven days to allow withdrawal bleeding. Progesterone/progestogen-only rings are kept in for varying periods and replaced without a ring-free period. Rings are in various stages of research and development but a few, such as NuvaRing, have reached the market in some countries. Women find this method easy to use, effective, well tolerated and acceptable with no serious side-effects. Though the contraceptive efficacy of these vaginal rings is high, acceptability is yet to be established.

  15. Smoke Ring Physics

    NASA Astrophysics Data System (ADS)

    Huggins, Elisha

    2011-11-01

    The behavior of smoke rings, tornados, and quantized vortex rings in superfluid helium has many features in common. These features can be described by the same mathematics we use when introducing Ampère's law in an introductory physics course. We discuss these common features.

  16. The Fermilab recycler ring

    SciTech Connect

    Martin Hu

    2001-07-24

    The Fermilab Recycler is a permanent magnet storage ring for the accumulation of antiprotons from the Antiproton Source, and the recovery and cooling of the antiprotons remaining at the end of a Tevatron store. It is an integral part of the Fermilab III luminosity upgrade. The following paper describes the design features, operational and commissioning status of the Recycler Ring.

  17. Smoke Ring Physics

    ERIC Educational Resources Information Center

    Huggins, Elisha

    2011-01-01

    The behavior of smoke rings, tornados, and quantized vortex rings in superfluid helium has many features in common. These features can be described by the same mathematics we use when introducing Ampere's law in an introductory physics course. We discuss these common features. (Contains 7 figures.)

  18. EBT ring physics

    SciTech Connect

    Uckan, N.A.

    1980-04-01

    This workshop attempted to evaluate the status of the current experimental and theoretical understanding of hot electron ring properties. The dominant physical processes that influence ring formation, scaling, and their optimal behavior are also studied. Separate abstracts were prepared for each of the 27 included papers. (MOW)

  19. Telemetry carrier ring and support

    NASA Technical Reports Server (NTRS)

    Wakeman, Thomas G. (Inventor)

    1992-01-01

    A telemetry carrier ring for use in a gas turbine engine includes an annular support ring connected to the engine and an annular carrier ring coupled to the support ring, each ring exhibiting different growth characteristics in response to thermal and mechanical loading. The carrier ring is coupled to the support ring by a plurality of circumferentially spaced web members which are relatively thin in an engine radial direction to provide a predetermined degree of radial flexibility. the web members have a circumferential width and straight axial line of action selected to transfer torque and thrust between the support ring and the carrier ring without substantial deflection. The use of the web members with radial flexibility provides compensation between the support ring and the carrier ring since the carrier ring grows at a different rate than the supporting ring.

  20. An SAE high speed ring bus overview

    NASA Astrophysics Data System (ADS)

    Kroeger, Brian W.; Shih, Hubert

    An overview of the protocols and important features of the SAE high-speed ring bus (HSRB) standard is presented here, along with the functional design of a typical ring interface unit architecture. The counterrotating ring topology, with both loopback and bypass mechanisms, provides the high degree of fault tolerance desirable in many military and avionic systems. The error-detection, fault-detection, and recovery mechanisms are briefly described to illustrate the robustness of the HSRB system. The reserved-priority token-passing protocol is shown to provide efficient and deterministic performance, uselful in real-time applications where messages must be transmitted predictably, quickly, and reliably.

  1. Mysteries of the ringed planets. [colloquium review

    NASA Technical Reports Server (NTRS)

    Cuzzi, J. N.

    1982-01-01

    An assessment is presented of the recent progress in the theory of planetary rings which was in evidence at the IAU's recent, 75th Colloquium. Observational material was dominated by spacecraft data, and theoretical consideration of the problems posed comes predominantly from gravitational mechanics. An understanding of collective effects, in light of both fluid mechanical and statistical mechanical methodologies, is being approached, and the importance of electromagnetic phenomena studies is noted. Voyager observations of Saturn's rings, and accumulating data from stellar occultations by the rings of Uranus, provided most of the observational material. Jupiter's faint ring was closely examined by the 1979 Voyager flight. These three known ring systems are found to exhibit such family resemblances as their proximity to the parent planet and magnetospheric environment.

  2. Ring chromosome 4.

    PubMed Central

    McDermott, A; Voyce, M A; Romain, D

    1977-01-01

    A mentally and physically retarded boy with a 46,XY,ring (4) (p16q35) chromosome complement is described. Chromosome banding showed that the amount of chromosome material deleted from the ring chromosome 4 was minimal, apparently no more than the telomeres. Chromosomal aberrations appear to be restricted to the production of double-sized dicentric rings, and aneuploidy. The mosiacism resulting from the behavioural peculiarities of ring chromosomes is described as dynamic mosaicism. It is suggested that the clinical features associated with this ring chromosome are more likely to be the result of the effects of a diploid/monosomy 4/polysomy 4 mosaicism than to the deficiency of the telomeric regions of the chromosome. Images PMID:881718

  3. Jupiter's Rings: Sharpest View

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The New Horizons spacecraft took the best images of Jupiter's charcoal-black rings as it approached and then looked back at Jupiter. The top image was taken on approach, showing three well-defined lanes of gravel- to boulder-sized material composing the bulk of the rings, as well as lesser amounts of material between the rings. New Horizons snapped the lower image after it had passed Jupiter on February 28, 2007, and looked back in a direction toward the sun. The image is sharply focused, though it appears fuzzy due to the cloud of dust-sized particles enveloping the rings. The dust is brightly illuminated in the same way the dust on a dirty windshield lights up when you drive toward a 'low' sun. The narrow rings are confined in their orbits by small 'shepherding' moons.

  4. Design of a loop resonator with a split-ring-resonator (SRR) for a human-body coil in 3 T MRI systems

    NASA Astrophysics Data System (ADS)

    Son, Hyeok Woo; Cho, Young Ki; Kim, Byung Mun; Back, Hyun Man; Yoo, Hyoungsuk

    2016-04-01

    A new radio-frequency (RF) resonator for Nuclear Magnetic Resonance (NMR) imaging at clinical magnetic resonance imaging (MRI) systems is proposed in this paper. An approach based on the effects of the properties of metamaterials in split-ring resonators (SRRs) is used to design a new loop resonator with a SRR for NMR imaging. This loop resonator with a SRR is designed for NMR imaging at 3 T MRI systems. The 3D electromagnetic simulation was used to optimize the design of the proposed RF resonator and analyze it's performance at 3 T MRI systems. The proposed RF resonator provides strong penetrating magnetic fields at the center of the human phantom model, approximately 10%, as compared to the traditional loop-type RF resonator used for NMR imaging at clinical MRI systems. We also designed an 8-channel body coil for human-body NMR imaging by using the proposed loop resonator with a SRR. This body coil also produces more homogeneous and highly penetrating magnetic fields into the human phantom model.

  5. Thermal and dynamic analysis of the RING (Radiatively-cooled, Inertially-driven Nuclear Generator) power system radiator

    NASA Astrophysics Data System (ADS)

    Apley, Walter J.; Babb, Albert L.

    1989-01-01

    The nuclear option for a space-based power system appears most suitable for missions that require long-term, sustained operation at power levels above 100 kWe. Systems currently available operate at relatively low thermal efficiencies (6 to 10 percent). Thus, a 100 kWe system must discharge nearly 2 MWth of waste heat through the comparatively inefficient process of radiative cooling. The impact of the resultant radiator assembly size on overall power system weight is significant, and has led to proposals for radiators with potentially higher efficiencies. Examples include the liquid droplet radiator, fabric radiator, bubble membrane radiator, rotating film radiator, and dust radiator.

  6. New Horizons Imaging of Jupiter's Main Ring

    NASA Astrophysics Data System (ADS)

    Throop, Henry B.; Showalter, Mark Robert; Dones, Henry C. Luke; Hamilton, D. P.; Weaver, Harold A.; Cheng, Andrew F.; Stern, S. Alan; Young, Leslie; Olkin, Catherine B.; New Horizons Science Team

    2016-10-01

    New Horizons took roughly 520 visible-light images of Jupiter's ring system during its 2007 flyby, using the spacecraft's Long-Range Reconnaissance Imager (LORRI). These observations were taken over nine days surrounding Jupiter close-approach. They span a range in distance of 30 - 100 RJ, and a phase angle range of 20 - 174 degrees. The highest resolution images -- more than 200 frames -- were taken at a resolution approaching 20 km/pix.We will present an analysis of this dataset, much of which has not been studied in detail before. Our results include New Horizons' first quantitative measurements of the ring's intrinsic brightness and variability. We will also present results on the ring's azimuthal and radial structure. Our measurements of the ring's phase curve will be used to infer properties of the ring's dust grains.Our results build on the only previous analysis of the New Horizons Jupiter ring data set, presented in Showalter et al (2007, Science 318, 232-234), which detected ring clumps and placed a lower limit on the population of undetected ring-moons.This work was supported by NASA's OPR program.

  7. Ring-Resonator/Sol-Gel Interferometric Immunosensor

    NASA Technical Reports Server (NTRS)

    Bearman, Gregory; Cohen, David

    2007-01-01

    A proposed biosensing system would be based on a combination of (1) a sensing volume containing antibodies immobilized in a sol-gel matrix and (2) an optical interferometer having a ring resonator configuration. The antibodies would be specific to an antigen species that one seeks to detect. In the ring resonator of the proposed system, light would make multiple passes through the sensing volume, affording greater interaction length and, hence, greater antibody- detection sensitivity.

  8. Behavioral Mapless Navigation Using Rings

    NASA Technical Reports Server (NTRS)

    Monroe, Randall P.; Miller, Samuel A.; Bradley, Arthur T.

    2012-01-01

    This paper presents work on the development and implementation of a novel approach to robotic navigation. In this system, map-building and localization for obstacle avoidance are discarded in favor of moment-by-moment behavioral processing of the sonar sensor data. To accomplish this, we developed a network of behaviors that communicate through the passing of rings, data structures that are similar in form to the sonar data itself and express the decisions of each behavior. Through the use of these rings, behaviors can moderate each other, conflicting impulses can be mediated, and designers can easily connect modules to create complex emergent navigational techniques. We discuss the development of a number of these modules and their successful use as a navigation system in the Trinity omnidirectional robot.

  9. Thermal and dynamic analysis of the RING (Radiatively-cooled, Inertially-driven Nuclear Generator) power system radiator

    SciTech Connect

    Apley, W.J.; Babb, A.L.

    1989-01-01

    The nuclear option for a space-based power system appears most suitable for missions that require long-term, sustained operation at power levels above 100 kWe. Systems currently available operate at relatively low thermal efficiencies (6--10%). Thus, a 100 kWe system must discharge nearly 2 MWth of waste heat through the comparatively inefficient process of radiative cooling. The impact of the resultant radiator assembly size on overall power system weight is significant, and has led to proposals for radiators with potentially higher efficiencies. Examples include the: liquid droplet radiator; fabric radiator; bubble membrane radiator; rotating film radiator; and dust radiator. 14 refs., 2 figs., 2 tabs.

  10. The Secular Evolution of a Close Ring-Satellite System: The Excitation of Spiral Bending Waves at a Nearby Gap Edge

    NASA Astrophysics Data System (ADS)

    Hahn, Joseph M.

    2007-08-01

    The secular perturbations exerted by an inclined satellite orbiting in a gap in a broad planetary ring tend to excite the inclinations of the nearby ring particles, and the ring's self-gravity can allow that disturbance to propagate away in the form of a spiral bending wave. The amplitude of this spiral bending wave is determined, as well as the wavelength, which shrinks as the waves propagate outward due to the effects of the central planet's oblateness. The excitation of these bending waves also damps the satellite's inclination I. This secular I damping is also compared to the inclination excitation that is due to the satellite's many other vertical resonances in the ring, and the condition for inclination damping is determined. The secular I damping is likely responsible for confining the orbits of Saturn's two known gap-embedded moons, Pan and Daphnis, to the ring plane.

  11. The postman always rings twice: two cases of shotgun deaths associated with an unconventional home security alarm system.

    PubMed

    Asirdizer, Mahmut; Turkmen, Nursel; Akan, Okan; Yavuz, Mehmet Sunay

    2014-06-01

    Injury and death cases caused by booby traps are not common in forensic medicine practice. Besides, installation of booby traps including firearms is generally for suicidal and rarely for homicidal purposes. Although few patents were described about home security alarm system that were created by firearms in the United States, 1 sample of injury with a similar unconventional mechanism of home safety system was reported by Asirdizer and Yavuz in 2009. In the published case report, the story of an electrical technician who was invited to a summer house by the homeowner to check the home security alarm system was reported. In the so-called report, he was stated to be injured by the shotgun attached to the unconventional home security alarm system while checking the system. As a result, the homeowner was convicted of a possible intent to cause a life-threatening injury to the technician.The so-called homeowner and his wife died by the same shotgun attached to the same unconventional home security alarm system 4 years on from the first event. In the present case report, we have aimed to present the findings of the crime scene and the autopsies of these unusual 2 deaths and to discuss individual and legal factors in paving the way for the deaths of 2 people.

  12. Seal ring installation tool

    NASA Technical Reports Server (NTRS)

    Haselmaier, L. Haynes (Inventor)

    2004-01-01

    A seal ring tool that allows an installer to position a primary seal ring between hub ends of pipe flanges that are being assembled together. The tool includes a pivoting handle member and extension arms attached to the pivoting handle member. The ends of the arms have side indentation type longitudinal grooves angled toward one another for holding the primary seal ring in place between the hubs of respective pipes that are to be attached together. The arms of the tool can also have flat sides that can be used to abut against an optional second larger seal that is supported within a groove in one of the hub ends so that the second hub end can then be moved against the other side of the primary seal ring. Once the seal ring is positioned between the pipe hubs, the pipe hubs can be moved about the seal ring due to the flat sides of the arms of the tool. The tool eliminates the chances of damaging and contaminating seal rings being installed within pipe hubs that are being attached to one another.

  13. Saturn's Ring: Pre-Cassini Status and Mission Goals

    NASA Technical Reports Server (NTRS)

    Cuzzi, Jeff N.; DeVincenzi, Donald L. (Technical Monitor)

    1999-01-01

    In November 1980, and again in August 1981, identical Voyager spacecraft flew through the Saturn system, changing forever the way we think about planetary rings. Although Saturn's rings had been the only known ring system for three centuries, a ring system around Uranus had been discovered by stellar occultations from Earth in 1977, and the nearly transparent ring of Jupiter was imaged by Voyager in 1979 (the presence of material there had been inferred from charged particle experiments on Pioneer 10 and 11 several years earlier). While Saturn had thus temporarily lost its uniqueness as having the only ring system, with Voyager it handily recaptured the role of having the most fascinating one. The Voyager breakthroughs included spiral density and bending waves such as cause galactic structure; ubiquitous fine-scale radial 'irregular' structure, with the appearance of record-grooves; regional and local variations in particle color; complex, azimuthally variable ring structure; empty gaps in the rings, some containing very regular, sharp-edged, elliptical rings and one containing both a small moonlet and incomplete arcs of dusty material; and shadowy 'spokes' that flicker across the main rings. One of the paradigm shifts of this period was the realization that many aspects of planetary rings, and even the ring systems themselves, could be 'recent' on geological timescales. These early results are reviewed and summarized in the Arizona Space Science series volumes 'Saturn'. (An excellent review of ring dynamics at a formative stage is by Goldreich and Tremaine.) From the mid 1980's to the time of this writing, progress has been steady, while at a less heady pace, and some of the novel ring properties revealed by Voyager 1 and 2 are beginning to be better understood. It is clearly impossible to cite, much less review, every advance over the last decade; however, below we summarize the main advances in understanding of Saturn's rings since the mid 1980's, in the context

  14. 1993 Evaluation of steel ring standards for magnetic particle inspection

    SciTech Connect

    Bates, B.; Hagemaier, D.; Petty, J.; Armstrong, C.

    1996-10-01

    The Ketos ring standard manufactured from AISI Type 01 (.90 carbon) tool steel has become part of certain US magnetic particle standards such as MIL-STD-1949. The rings are used to verify system performance and for sensitivity evaluation for magnetic particle materials. Some controversy exists concerning the use of the steel ring as a reference standard for the following reasons: inconsistencies in hole detectability have been noted between various rings caused by differences in magnetic permeability as a result of variations in annealing; the use of magnetic particle indication evaluation for ring standard certification is subject to variations in particle concentration, sensitivity, and visual subjectivity; and the proposed introduction of new materials in the manufacture of ring standards. This report describes an evaluation of rings manufactured of different materials and different annealed states. A suggested method for qualifying a newly manufactured ring as a certified reference standard is also described.

  15. CASSINI UVIS STELLAR OCCULTATION OBSERVATIONS OF SATURN's RINGS

    SciTech Connect

    Colwell, J. E.; Jerousek, R. G.; Pettis, D.; Bradley, E. T.; Esposito, L. W.; Sremcevic, M.

    2010-12-15

    The Cassini spacecraft's Ultraviolet Imaging Spectrograph (UVIS) includes a high-speed photometer (HSP) that has observed more than 100 stellar occultations by Saturn's rings. Here, we document a standardized technique applied to the UVIS-HSP ring occultation datasets delivered to the Planetary Data System as higher level data products. These observations provide measurements of ring structure that approaches the scale of the largest common ring particles ({approx}5 m). The combination of multiple occultations at different viewing geometries enables reconstruction of the three-dimensional structure of the rings. This inversion of the occultation data depends on accurate calibration of the data so that occultations of different stars taken at different times and under different viewing conditions can be combined to retrieve ring structure. We provide examples of the structure of the rings as seen from several occultations at different incidence angles to the rings, illustrating changes in the apparent structure with viewing geometry.

  16. Dynamics of the Uranian Rings

    NASA Technical Reports Server (NTRS)

    Dermott, S. F.

    1984-01-01

    Some of the problems of the shepherding satellite model of Goldreich ant tremaine are discussed. The following topics are studied: (1) optical depths of the all the observed narrow rings; (2) satellite and ring separation timescales; (3) ring edge sharpness; (4) shock formation in narrow rings; (5) the existence of small satellites near the Uranian rings; and (6) the apse and node alignments of the eccentric and inclined rings.

  17. Heavy ion storage rings

    SciTech Connect

    Schuch, R.

    1987-01-01

    A brief overview of synchrotron storage rings for heavy ions, which are presently under construction in different accelerator laboratories is given. Ions ranging from protons up to uranium ions at MeV/nucleon energies will be injected into these rings using multiturn injection from the accelerators available or being built in these laboratories. After injection, it is planned to cool the phase space distribution of the ions by merging them with cold electron beams or laser beams, or by using stochastic cooling. Some atomic physics experiments planned for these rings are presented.

  18. Alternative parallel ring protocols

    NASA Technical Reports Server (NTRS)

    Mukkamala, R.; Foudriat, E. C.; Maly, Kurt J.; Kale, V.

    1990-01-01

    Communication protocols are know to influence the utilization and performance of communication network. The effect of two token ring protocols on a gigabit network with multiple ring structure is investigated. In the first protocol, a mode sends at most one message on receiving a token. In the second protocol, a mode sends all the waiting messages when a token is received. The behavior of these protocols is shown to be highly dependent on the number of rings as well as the load in the network.

  19. Supernumerary small ring chromosome.

    PubMed Central

    Kaffe, S; Kim, H J; Hsu, L Y; Brill, C B; Hirschhorn, K

    1977-01-01

    A supernumerary small ring chromosome was found in 30% of cultured peripheral leucocytes and 50% of skin fibroblasts in a 6-year-old boy with mild mental retardation and midline cleft palate. The extra chromosome appeared to carry a densely staining region on Giemsa banding. The banding patterns of the remaining 46 chromosomes were normal. C banding indicated that the ring chromosome contained mainly centromeric constitutive heterochromatin. Chromosome analysis of both parents showed normal karyotypes by both conventional and banding techniques; thus the origin of the ring chromosome could not be determined. Images PMID:604496

  20. Theodolite Ring Lights

    NASA Technical Reports Server (NTRS)

    Clark, David

    2006-01-01

    Theodolite ring lights have been invented to ease a difficulty encountered in the well-established optical-metrology practice of using highly reflective spherical tooling balls as position references. A theodolite ring light produces a more easily visible reflection and eliminates the need for an autocollimating device. A theodolite ring light is a very bright light source that is well centered on the optical axis of the instrument. It can be fabricated, easily and inexpensively, for use on a theodolite or telescope of any diameter.

  1. Microwave Observations on Saturn's Main Rings

    NASA Astrophysics Data System (ADS)

    Zhang, Zhimeng; Hayes, Alexander; Janssen, Michael A.; Nicholson, Philip D.; Cuzzi, Jeffrey N.; de Pater, Imke; Dunn, David; Hedman, Matthew M.; Estrada, Paul R.

    2016-10-01

    Despite considerable study, Saturn's rings continue to challenge current theories for their provenance. Water ice comprises the bulk of Saturn's rings, yet it is the small fraction of non-icy material that is arguably more valuable in revealing clues about the system's origin and age. Herein, we present new measurements of the non-icy material fraction in Saturn's main rings, determined from microwave observations obtained by Cassini Radar and EVLA.Our Cassini Radar observations in the C Ring show an exceptionally high brightness at near-zero azimuthal angles, suggesting a high porosity of 70%-75% for the particles. Furthermore, most regions in the C ring contain about 1-2% silicates while with an enhanced abundance concentrated in the middle C ring reaching a maximum of 6%-11%. We proposed that the C ring has been continuously polluted by meteoroid bombardment for 15-90Myr, while the middle C ring was further contaminated by an incoming Centaur disrupted by Saturn tidal force. Owing to the B ring's high opacity, the particles there are likely to have 85% - 90% porosity, with corresponding non-icy material fractions of ~ 0.3% - 0.5% in the inner and outer B ring, and ~0.1% - 0.2% in the middle regions. For the A ring interior to the Encke gap, the derived non-icy material is ~0.2% - 0.3% everywhere for porosities ranging from 55% - 90%. Finally, our results for the Cassini Division indicate a non-icy material fraction of ~1% - 2% similar to most regions in the C ring, except that the Cassini Division particles are more likely to contain ~ 90% porosity due to the high opacity there. Our results here further support the idea that Saturn's rings may be less than 150 Myr old suggesting an origin scenario in which the rings are derived from the relatively recent breakup of an icy moon.Furthermore, we calibrated and analyzed multi-wavelengths EVLA observation at wavelengths ranging from 0.7cm to 13cm. As the array operates in a wavelength regime where the absorption

  2. Satellite And Propeller Migration In Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Crida, Aurelien; Charnoz, S.; Papaloizou, J.; Salmon, J.

    2009-09-01

    Saturn's rings host satellites like Pan and Daphnis, and smaller bodies like the recently discovered propellers (Tiscareno et al. 2006). These bodies interact gravitationally with the rings. Actually, the resulting perturbations on the ring system have revealed the presence of embedded objects (the Encke and Keeler gaps associated with Pan and Daphnis respectively, the little two-folded structures called propellers tracing the scattering of ring particles by some embedded small objects). Reciprocally, the rings must act on the embedded bodies, leading to their migration. Here, we study how the standard theory of planetary migration applies in Saturn's ring, where the pressure is negligible in contrast with standard protoplanetary disks. Pan and Daphnis should be in standard type II migration, governed by the global disk evolution. Therefore, their presence and position provide constraints on the history of the A-ring, which can be studied using numerical simulations of disk-satellite interactions. The propellers are fully embedded in the disc, and therefore should be subject to type I migration. The simple impulse approximation used by Lin and Papaloi zou (1979) to derive the one-sided torque is particularly suited to this case. Refining their calculation, taking density variations into account, and discussing the possibility for these bodies to enter the type III, runaway regime of migration, we aim at estimating a possible migration rate for these propellers, to be compared to the system life time.

  3. High-Speed Ring Bus

    NASA Technical Reports Server (NTRS)

    Wysocky, Terry; Kopf, Edward, Jr.; Katanyoutananti, Sunant; Steiner, Carl; Balian, Harry

    2010-01-01

    is no centralized arbitration or bus granting. The JPL design provides for autonomous synchronization of the nodes on the ring bus. An address-synchronous latency adjust buffer (LAB) has been designed that cannot get out of synchronization and needs no external input. Also, a priority-driven cable selection behavior has been programmed into each unit on the ring bus. This makes the bus able to connect itself up, according to a maximum redundancy priority system, without the need for computer intervention at startup. Switching around a failed or switched-off unit is also autonomous. The JPL bus provides a map of all the active units for the host computer to read and use for fault management. With regard to timing, this enhanced bus recognizes coordinated timing on a spacecraft as critical and addresses this with a single source of absolute and relative time, which is broadcast to all units on the bus with synchronization maintained to the tens of nanoseconds. Each BIU consists of up to five programmable triggers, which may be programmed for synchronization of events within the spacecraft of instrument. All JPL-formatted data transmitted on the ring bus are automatically time-stamped.

  4. On the possible triple central star system of PN SuWt 2: no ménage à trois at the heart of the Wedding Ring

    NASA Astrophysics Data System (ADS)

    Jones, David; Boffin, Henri M. J.

    2017-04-01

    SuWt 2 is a planetary nebula consisting of a bright ring-like waist from which protrude faint extended lobes - a morphology believed to be typical of progenitors which have experienced a close-binary evolution. Previous observations of NSV 19992, the star at the projected centre of SuWt 2, have found it to comprise two A-type stars in a 4.9 d eclipsing orbit, neither of which could be the nebular progenitor. Radial velocity studies provided a hint that the systemic velocity of this double A-type binary might be varying over time, suggesting the presence of a third component hypothesized to be the nebular progenitor. Here, we present an extensive radial velocity monitoring study of NSV 19992, performed with the high-resolution Ultraviolet and Visual Echelle Spectrograph mounted on the European Southern Observatory's Very Large Telescope, in order to constrain the possible variation in the systemic velocity of the A-type binary and its relation to the progenitor of SuWt 2. The observations, acquired over a period of approximately one year, show no evidence of variability in the systemic velocity of NSV 19992. Combining these new observations with previous high-resolution spectroscopy demonstrates that the systemic velocity is also stable over much longer periods and, moreover, is distinct from that of SuWt 2, strongly indicating that the two are not associated. We conclude that NSV 19992 is merely a field star system, by chance lying in the same line of sight as the nebular centre, and that it bears no relation to SuWt 2 or its, as yet unidentified, central star(s).

  5. Cag-delta (Cag3) protein from the Helicobacter pylori 26695 cag type IV secretion system forms ring-like supramolecular assemblies.

    PubMed

    Smart, Jonathan; Fouillen, Aurélien; Casu, Bastien; Nanci, Antonio; Baron, Christian

    2017-01-01

    Helicobacter pylori is an important cause of gastric pathologies and persistent infection can lead to stomach cancer. Virulent H. pylori strains encode a type IV secretion system responsible for translocation of the oncogenic CagA protein into cells of the gastric mucosa. Gene HP0522 encodes the essential component Cagδ (Cag3), and we show by gel filtration and cross-linking that purified Cagδ forms high molecular mass complexes. In contrast, its interaction partner CagT is mostly monomeric, but co-fractionates after gel filtration. Analysis by transmission electron microscopy revealed that purified Cagδ complexes can self-assemble ring-like structures. Cagδ-overexpressing Escherichia coli exhibits membrane-associated circular profiles in regions of the cell envelope with intense immunogold labelling with a Cagδ-specific antiserum. Our results suggest that Cagδ has the capacity to form macromolecular structures contributing to the assembly of the type IV secretion system.

  6. Saturn's dynamic D ring

    USGS Publications Warehouse

    Hedman, M.M.; Burns, J.A.; Showalter, M.R.; Porco, C.C.; Nicholson, P.D.; Bosh, A.S.; Tiscareno, M.S.; Brown, R.H.; Buratti, B.J.; Baines, K.H.; Clark, R.

    2007-01-01

    The Cassini spacecraft has provided the first clear images of the D ring since the Voyager missions. These observations show that the structure of the D ring has undergone significant changes over the last 25 years. The brightest of the three ringlets seen in the Voyager images (named D72), has transformed from a narrow, <40-km wide ringlet to a much broader and more diffuse 250-km wide feature. In addition, its center of light has shifted inwards by over 200 km relative to other features in the D ring. Cassini also finds that the locations of other narrow features in the D ring and the structure of the diffuse material in the D ring differ from those measured by Voyager. Furthermore, Cassini has detected additional ringlets and structures in the D ring that were not observed by Voyager. These include a sheet of material just interior to the inner edge of the C ring that is only observable at phase angles below about 60??. New photometric and spectroscopic data from the ISS (Imaging Science Subsystem) and VIMS (Visual and Infrared Mapping Spectrometer) instruments onboard Cassini show the D ring contains a variety of different particle populations with typical particle sizes ranging from 1 to 100 microns. High-resolution images reveal fine-scale structures in the D ring that appear to be variable in time and/or longitude. Particularly interesting is a remarkably regular, periodic structure with a wavelength of ??? 30 ?? km extending between orbital radii of 73,200 and 74,000 km. A similar structure was previously observed in 1995 during the occultation of the star GSC5249-01240, at which time it had a wavelength of ??? 60 ?? km. We interpret this structure as a periodic vertical corrugation in the D ring produced by differential nodal regression of an initially inclined ring. We speculate that this structure may have formed in response to an impact with a comet or meteoroid in early 1984. ?? 2006 Elsevier Inc. All rights reserved.

  7. Ultrasonic Newton's rings

    SciTech Connect

    Hsu, D.K. ); Dayal, V. )

    1992-03-09

    Interference fringes due to bondline thickness variation were observed in ultrasonic scans of the reflected echo amplitude from the bondline of adhesively joined aluminum skins. To demonstrate that full-field interference patterns are observable in point-by-point ultrasonic scans, an optical setup for Newton's rings was scanned ultrasonically in a water immersion tank. The ultrasonic scan showed distinct Newton's rings whose radii were in excellent agreement with the prediction.

  8. Bending the Rings

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Saturn's rings appear strangely warped in this view of the rings seen through the upper Saturn atmosphere.

    The atmosphere acts like a lens in refracting (bending) the light reflected from the rings. As the rings pass behind the overexposed limb (edge) of Saturn as seen from Cassini, the ring structure appears to curve downward due to the bending of the light as it passes through the upper atmosphere.

    This image was obtained using a near-infrared filter. The filter samples a wavelength where methane gas does not absorb light, thus making the far-off rings visible through the upper atmosphere.

    By comparing this image to similar ones taken using filters where methane gas does absorb, scientists can estimate the vertical profile of haze and the abundance of methane in Saturn's high atmosphere.

    The image was taken in visible light with the Cassini spacecraft narrow-angle camera on April 14, 2005, through a filter sensitive to wavelengths of infrared light centered at 938 nanometers and at a distance of approximately 197,000 kilometers (123,000 miles) from Saturn. The image scale is 820 meters (2,680 feet) per pixel.

  9. Facile Access to Cyclooctanoid Ring Systems via Microwave-Assisted Tandem 6-exo dig Cyclization-Rearrangement Sequence

    PubMed Central

    Feldman, Aaron W.; Ovaska, Sami I.; Ovaska, Timo V.

    2014-01-01

    Appropriately substituted 5-alkyn-1-ol systems bearing a nitrile moiety at the triple bond serve as versatile precursors to a variety of cyclooctenone derivatives via a “one-pot” base-catalyzed oxyanionic 6-exo dig cyclization/Claisen rearrangement sequence under microwave irradiation. It was found that the initially formed cyclic intermediate consists of a mixture of endo and exocyclic isomers, which appear to be in equilibrium under the reaction conditions. However, the only observed products from these reactions are α-cyano substituted cyclooctenones, derived from the exocyclic dihydrofuran intermediates. PMID:24994941

  10. Performance of a two-mirror, four-reflection, ring-field optical system at {lambda}=13 nm

    SciTech Connect

    La Fontaine, B.; Gaines, D.P.; Kania, D.R.; Sommargren, G.E.; Baker, S.L.; Ciarlo, D.

    1996-05-24

    Performance of an Extreme Ultraviolet Lithography (EUVL) imaging optic was characterized by printing resolution test images in resist. While features as small as 0.137 {mu}m were successfully printed, a resolution of 0.175 {mu}m better represents the performance of the system over the full 0.9 mm{sup 2} image field. The contrast of the aerial image was estimated to be about 40% or less for the fine features printed. This low contrast value is attributed to a degradation of the modulation transfer function due to presence of scattered light in the image.

  11. Alkoxyallene-ynes: Selective Preparation of Bicyclo[5.3.0] Ring Systems Including a δ-Alkoxy Cyclopentadienone.

    PubMed

    Tap, Aurélien; Lecourt, Camille; Dhambri, Sabrina; Arnould, Mathieu; Galvani, Gilles; Nguyen, Van Buu Olivier; Jouanneau, Morgan; Férézou, Jean-Pierre; Ardisson, Janick; Lannou, Marie-Isabelle; Sorin, Geoffroy

    2016-03-24

    The development of an intramolecular rhodium(I)-catalyzed Pauson-Khand reaction of alkoxyallene-ynes with a proximal alkoxy group is reported. This reaction, in the presence of a [Rh(cycloocta-1,5-diene)Cl]2/propane-1,3-diylbis(diphenylphosphane) system under a CO atmosphere, constitutes a powerful tool for selectively accessing carbo- and heterobicyclo[5.3.0] frameworks featuring an enol ether moiety. Through this procedure, a straightforward access to guaiane skeletons with a tertiary hydroxy group at the C10 position was achieved.

  12. Decoding Debris System Substructures: Imprints of Planets/Planetesimals and Signatures of Extrinsic Influences on Material in Ring-Like Disks

    NASA Astrophysics Data System (ADS)

    Schneider, Glenn

    2014-10-01

    How do circumstellar (CS) disks evolve and form planetary systems? Is our solar system's two-component debris disk (DD) typical? Are planets implicated by evidence of dynamical stirring in disks? Are DD architectures correlated with stellar mass? To address these highly-compelling questions of fundamental astrophysical import, we propose follow-up STIS coronagraphy of five intermediate-inclination ring-like DDs. These images will provide unprecedented clarity, sensitivity, and photometric efficacy to: 1) Study the spatial distribution of dust as close as 0.2" from the host stars enabling us to infer the existence and properties of unseen co-orbiting planets, and to probe disk-planet interactions across stellar ages and spectral types; 2) Provide spatially resolved imaging within DD regions previously unsampled to significantly improve constraints on disk grain properties and radial segregation of grain populations as a function of stellocentric distance (and thus temperature); 3) Produce high-fidelity images of DD substructures for dynamical interpretation, constraining the possibilities for planetary system architectures; 4) Obtain deep images of regions beyond the primary, bright debris features to study small-grain populations that might be unbound from the system and affected by both extrinsic and intrinsic forces and may inform about the level of dynamical activity in the planetesimal belt; 5) Provide, through the HLA, the highest quality and most complete, value-added data products for a seminal legacy data set of spatially resolvable light-scattering DDs, thus enabling multi-wavelength investigations with new and future ground- and space-based facilities.

  13. Propellers in Saturn's rings

    NASA Astrophysics Data System (ADS)

    Sremcevic, M.; Stewart, G. R.; Albers, N.; Esposito, L. W.

    2014-04-01

    Theoretical studies and simulations have demonstrated the effects caused by objects embedded in planetary rings [5, 8]. Even if the objects are too small to be directly observed, each creates a much larger gravitational imprint on the surrounding ring material. These strongly depend on the mass of the object and range from "S" like propeller-shaped structures for about 100m-sized icy bodies to the opening of circumferential gaps as in the case of the embedded moons Pan and Daphnis and their corresponding Encke and Keeler Gaps. Since the beginning of the Cassini mission many of these smaller objects (~ 100m in size) have been identified in Saturn's A ring through their propeller signature in the images [10, 7, 9, 11]. Furthermore, recent Cassini observations indicate the possible existence of objects embedded even in Saturn's B and C ring [6, 2]. In this paper we present our new results about by now classical A ring propellers and more enigmatic B ring population. Due to the presence of self-gravity wakes the analysis of propeller brightness in ISS images always bears some ambiguity [7, 9] and consequently the exact morphology of propellers is not a settled issue. In 2008 we obtained a fortunate Cassini Ultraviolet Imaging Spectrograph (UVIS) occultation of the largest A ring propeller Bleriot. Utilizing Cassini ISS images we obtain Bleriot orbit and demonstrate that UVIS Persei Rev42 occultation did cut across Bleriot about 100km downstream from the center. The occultation itself shows a prominent partial gap and higher density outer flanking wakes, while their orientation is consistent with a downstream cut. While in the UVIS occultation the partial gap is more prominent than the flanking wakes, the features mostly seen in Bleriot images are actually flanking wakes. One of the most interesting aspects of the A ring propellers are their wanderings, or longitudinal deviations from a pure circular orbit [11]. We numerically investigated the possibility of simple moon

  14. Optical heterodyne detection for cavity ring-down spectroscopy

    DOEpatents

    Levenson, Marc D.; Paldus, Barbara A.; Zare, Richard N.

    2000-07-25

    A cavity ring-down system for performing cavity ring-down spectroscopy (CRDS) using optical heterodyne detection of a ring-down wave E.sub.RD during a ring-down phase or a ring-up wave E.sub.RU during a ring up phase. The system sends a local oscillator wave E.sub.LO and a signal wave E.sub.SIGNAL to the cavity, preferably a ring resonator, and derives an interference signal from the combined local oscillator wave E.sub.LO and the ring-down wave E.sub.RD (or ring-up wave E.sub.RU). The local oscillator wave E.sub.LO has a first polarization and the ring-down wave E.sub.RD has a second polarization different from the first polarization. The system has a combining arrangement for combining or overlapping local oscillator wave E.sub.LO and the ring-down wave E.sub.RD at a photodetector, which receives the interference signal and generates a heterodyne current I.sub.H therefrom. Frequency and phase differences between the waves are adjustable.

  15. Modeling The Size Distribution Of Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Albers, Nicole; Esposito, L. W.

    2007-10-01

    Spatial structures such as density and bending waves, self-gravity and moonlet wakes are among the better known pieces in the puzzle of the formation and evolution of Saturn's main rings. But also the actual sizes of ring particles are very important to understand the long-term behavior or the system. The Cassini mission is continuing to provide a wealth of new observations. Among those are the transient features, bright clumps, and brightness fluctuations in the rather mysterious F ring that are partially attributed to a population of moonlets hidden well within the bright core of the structure. Detections of opaque features during stellar occultations of the UVIS and VIMS instruments strongly support this idea. Further, the discovery of embedded moonlets in Saturn's A ring raises questions about the origin of these objects; not to forget about the km-sized moons, Pan and Daphnis, orbiting within the A ring. Are they remnants of a shattered moon or is it possible to accrete these objects from the surrounding ring material? Currently, the theory still lags behind the observations. Here, we employ a generalized kinetic approach aiming at the long-term evolution of the size distribution that cannot be achieved by current N-body simulations and discuss its implications for the evolution and origin of Saturn's rings.

  16. Transport effects due to particle erosion mechanisms. [in planetary rings

    NASA Technical Reports Server (NTRS)

    Durisen, R. H.

    1984-01-01

    Various processes can erode the surfaces of planetary ring particles. Recent estimates for Saturn's rings suggest that a centimeter-thick surface layer could be eroded from an isolated ring particle in less than 1000 yr by meteoroid impacts alone. The atoms, molecules, and chips ejected from ring particles by erosion will arc across the rings along elliptical orbits. For moderate ring optical depths, ejecta will be absorbed or inelastically scattered upon reintersecting the ring plane. Continuous exchange of ejecta between different ring regions can lead to net radial transport of mass and angular momentum, to changes in particle sizes, and to the buildup of chip regoliths several centimeters deep on the surfaces of ring particles. Because most of the erosional ejecta are not lost but merely exchanged over short distances, the net erosion rate of the surfaces of these ring particles will be much less than that estimated for an isolated particle. Numerical solutions for time-dependent ballistic transport under various assumptions suggest pile-up and spillover effects especially near regions of preexisting high optical depth contrast, such as the inner edges of A and B rings. Global redistribution could be significant over billions of years. Other features in planetary ring systems may be influenced by ballistic transport.

  17. Effect of defocusing distance on the contaminated surface of brass ring with nanosecond laser in a 3D laser scanning system

    NASA Astrophysics Data System (ADS)

    Zhao, Mali; Liu, Tiegen; Jiang, Junfeng; Wang, Meng

    2014-08-01

    Defocusing distance plays a key role in laser cleaning result and can be either positive or negative, depending on the focus position relative to the sample surface. In this paper, we investigate the effect of the defocusing distance on the cleaning efficiency of oxidized brass surface. The oxide layer from the surface of a brass ring was processed with a three dimensional (3-D) dynamically focused laser galvanometer scanning system. The relationship between removal efficiency of the oxide layer and the defocusing distance was analyzed. The sample surface topography, element content before and after the laser cleaning were analyzed by a scanning electron microscope (SEM) and Energy-dispersive X-ray spectroscopy (EDS), the surface quality after laser cleaning was analyzed by a Atomic Force Microscope (AFM), the chemical constituents of the oxide layer on the sample surface after being processed with different defocusing distances were examined by x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The results show that the ratios of Cu/O and Zn/O reach the maximum of 53.2 and 27.78 respectively when the defocusing distance is +0.5 mm. The laser pulses will lose the ability to remove the oxide layer from the substrate surface when the defocusing distance is larger than ±2 mm.

  18. The Vulnerability of Saskatchewan Water Resource System to Multi-Year Hydrologic Droughts at North and South Saskatchewan Rivers: Fusing Paleo Tree Ring Data with Stochastic Reconstruction

    NASA Astrophysics Data System (ADS)

    Nazemi, A.; Brunet, N.; Oegema, B.

    2015-12-01

    Despite having a semi-arid cold region, the province of Saskatchewan in western Canada is home to major agricultural activities. This is due to a reliable water supply in North and South Saskatchewan rivers (hereafter NSR and SSR), initiated from the Rocky Mountain headwaters in south western Alberta. The incoming interprovincial streamflow to Saskatchewan, however, is subject to significant annual variations due to natural climate variability, climate change as well as human use and regulation. Most importantly, severe multi-year hydrologic droughts in NSR and SSR have been observed within historical and paleo records. Such long-term low flow conditions can cause vulnerability in the water supply systems, particularly if combined with an increased irrigation demand, due to global warming, crop change, meteorological drought and/or irrigation expansion. This study aims at providing a novel use of long-term annual paleo streamflow records for monthly, multi-sector drought impact assessment. By considering tree ring-based reconstructed annual streamflow records, 10-year drought sequences with 100-year return periods were obtained at NSR and SSR. The annual sequences were converted to monthly flow hydrographs using a stochastic reconstruction scheme. The water resource system was then conditioned to multiple realizations of the monthly drought sequence and simulated under various scenarios for reservoir operation and increment in irrigation demand. Simulation results show that Saskatchewan can still maintain the Saskatchewan/Manitoba apportionment requirement, even under a 10-year drought and 10 folds increment in irrigation demand. Such severe drought sequence, nonetheless, cause significant decline in Saskatchewan's hydropower production, which is currently the most profitable water sector in the province. Changes in reservoir operation, however, can considerably mitigate the adverse effects of drought and increased irrigation demand on hydropower industry

  19. Non-Linear Dynamics of Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Esposito, L. W.

    2015-10-01

    Non-linear processes can explain why Saturn's rings are so active and dynamic. Ring systems differ from simple linear systems in two significant ways: 1. They are systems of granular material: where particle-to-particle collisions dominate; thus a kinetic, not a fluid description needed. We find that stresses are strikingly inhomogeneous and fluctuations are large compared to equilibrium. 2. They are strongly forced by resonances: which drive a non-linear response, pushing the system across thresholds that lead to persistent states. Some of this non-linearity is captured in a simple Predator-Prey Model: Periodic forcing from the moon causes streamline crowding; This damps the relative velocity, and allows aggregates to grow. About a quarter phase later, the aggregates stir the system to higher relative velocity and the limit cycle repeats each orbit, with relative velocity ranging from nearly zero to a multiple of the orbit average: 2-10x is possible. Results of driven N-body systems by Stuart Robbins: Even unforced rings show large variations; Forcing triggers aggregation; Some limit cycles and phase lags seen, but not always as predicted by predator-prey model. Summary of Halo Results: A predatorprey model for ring dynamics produces transient structures like 'straw' that can explain the halo structure and spectroscopy: Cyclic velocity changes cause perturbed regions to reach higher collision speeds at some orbital phases, which preferentially removes small regolith particles; Surrounding particles diffuse back too slowly to erase the effect: this gives the halo morphology; This requires energetic collisions (v ≈ 10m/sec, with throw distances about 200km, implying objects of scale R ≈ 20km); We propose 'straw'. Transform to Duffing Eqn : With the coordinate transformation, z = M2/3, the Predator-Prey equations can be combined to form a single second-order differential equation with harmonic resonance forcing. Ring dynamics and history implications: Moon

  20. Non-Linear Dynamics of Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Esposito, Larry W.

    2015-04-01

    Non-linear processes can explain why Saturn's rings are so active and dynamic. Ring systems differ from simple linear systems in two significant ways: 1. They are systems of granular material: where particle-to-particle collisions dominate; thus a kinetic, not a fluid description needed. We find that stresses are strikingly inhomogeneous and fluctuations are large compared to equilibrium. 2. They are strongly forced by resonances: which drive a non-linear response, pushing the system across thresholds that lead to persistent states. Some of this non-linearity is captured in a simple Predator-Prey Model: Periodic forcing from the moon causes streamline crowding; This damps the relative velocity, and allows aggregates to grow. About a quarter phase later, the aggregates stir the system to higher relative velocity and the limit cycle repeats each orbit, with relative velocity ranging from nearly zero to a multiple of the orbit average: 2-10x is possible Results of driven N-body systems by Stuart Robbins: Even unforced rings show large variations; Forcing triggers aggregation; Some limit cycles and phase lags seen, but not always as predicted by predator-prey model. Summary of Halo Results: A predator-prey model for ring dynamics produces transient structures like 'straw' that can explain the halo structure and spectroscopy: Cyclic velocity changes cause perturbed regions to reach higher collision speeds at some orbital phases, which preferentially removes small regolith particles; Surrounding particles diffuse back too slowly to erase the effect: this gives the halo morphology; This requires energetic collisions (v ≈ 10m/sec, with throw distances about 200km, implying objects of scale R ≈ 20km); We propose 'straw'. Transform to Duffing Eqn : With the coordinate transformation, z = M2/3, the Predator-Prey equations can be combined to form a single second-order differential equation with harmonic resonance forcing. Ring dynamics and history implications: Moon

  1. The Morphology of Saturn's F Ring

    NASA Astrophysics Data System (ADS)

    Murray, Carl D.; Cooper, N. J.; Attree, N. O.; Williams, G. A.

    2012-05-01

    The unusual nature of Saturn's F ring can be understood by considering the combined effects of gravity and collisional encounters. Gravitational perturbations from Prometheus and Pandora orbiting on either side of the ring produce the regular, streamer-channel phenomenon and also trigger the formation of clumps in the ring. There is also evidence for a population of 10km objects colliding with the ring at speeds of 30m/s to produce jets of material that subsequently undergo Keplerian shear to form the spiral strands that emanate from the core. Evidence for a population of 1km objects is also emerging; these appear to have similar orbits to the F ring core with collision speeds of 2m/s. The unprecedented opportunity to study the evolving F ring in detail with the Cassini spacecraft has resulted in new insights into the dynamics of the system. We present a review of our current knowledge of the F ring, primarily derived from Cassini ISS images. We show that geometric fits for the orbit of the core are consistent with those derived from occultations and yet still show variation due to the effect of Prometheus. Cassini images documented the formation and evolution of several prominent jets many of which are associated with collisions between the object S/2004 S 6 and the core. We show that smaller jet-like features have also been observed and clumps produced by Prometheus have been tracked in the core and strands. Finally we discuss possible models to explain the formation and evolution of the population of F ring objects and the varying activity observed in the ring.

  2. Ring correlations in random networks

    NASA Astrophysics Data System (ADS)

    Sadjadi, Mahdi; Thorpe, M. F.

    2016-12-01

    We examine the correlations between rings in random network glasses in two dimensions as a function of their separation. Initially, we use the topological separation (measured by the number of intervening rings), but this leads to pseudo-long-range correlations due to a lack of topological charge neutrality in the shells surrounding a central ring. This effect is associated with the noncircular nature of the shells. It is, therefore, necessary to use the geometrical distance between ring centers. Hence we find a generalization of the Aboav-Weaire law out to larger distances, with the correlations between rings decaying away when two rings are more than about three rings apart.

  3. DC-Powered Jumping Ring

    NASA Astrophysics Data System (ADS)

    Jeffery, Rondo N.; Amiri, Farhang

    2016-02-01

    The classroom jumping ring demonstration is nearly always performed using alternating current (AC), in which the ring jumps or flies off the extended iron core when the switch is closed. The ring jumps higher when cooled with liquid nitrogen (LN2). We have performed experiments using DC to power the solenoid and find similarities and significant differences from the AC case. In particular, the ring does not fly off the core but rises a short distance and then falls back. If the ring jumps high enough, the rising and the falling motion of the ring does not follow simple vertical motion of a projectile. This indicates that there are additional forces on the ring in each part of its motion. Four possible stages of the motion of the ring with DC are identified, which result from the ring current changing directions during the jump in response to a changing magnetic flux through the moving ring.

  4. Propellers in Saturn's rings

    NASA Astrophysics Data System (ADS)

    Sremcevic, M.; Stewart, G. R.; Albers, N.; Esposito, L. W.

    2013-12-01

    Theoretical studies and simulations have demonstrated the effects caused by objects embedded in planetary rings. Even if the objects are too small to be directly observed, each creates a much larger gravitational imprint on the surrounding ring material. These strongly depend on the mass of the object and range from "S" like propeller-shaped structures for about 100m-sized icy bodies to the opening of circumferential gaps as in the case of the embedded moons Pan and Daphnis and their corresponding Encke and Keeler Gaps. Since the beginning of the Cassini mission many of these smaller objects (~<500m in size) have been indirectly identified in Saturn's A ring through their propeller signature in the images. Furthermore, recent Cassini observations indicate the possible existence of objects embedded even in Saturn's B and C ring. In this paper we present evidence for the existence of propellers in Saturn's B ring by combining data from Cassini Ultraviolet Imaging Spectrograph (UVIS) and Imaging Science Subsystem (ISS) experiments. We show evidence that B ring seems to harbor two distinct populations of propellers: "big" propellers covering tens of degrees in azimuth situated in the densest part of B ring, and "small" propellers in less dense inner B ring that are similar in size and shape to known A ring propellers. The population of "big" propellers is exemplified with a single object which is observed for 5 years of Cassini data. The object is seen as a very elongated bright stripe (40 degrees wide) in unlit Cassini images, and dark stripe in lit geometries. In total we report observing the feature in images at 18 different epochs between 2005 and 2010. In UVIS occultations we observe this feature as an optical depth depletion in 14 out of 93 occultation cuts at corrotating longitudes compatible with imaging data. Combining the available Cassini data we infer that the object is a partial gap located at r=112,921km embedded in the high optical depth region of the B

  5. Piston Ring Pressure Distribution

    NASA Technical Reports Server (NTRS)

    Kuhn, M.

    1943-01-01

    The discovery and introduction of the internal combustion engine has resulted in a very rapid development in machines utilizing the action of a piston. Design has been limited by the internal components of the engine, which has been subjected to ever increasing thermal and mechanical stresses, Of these internal engine components, the piston and piston rings are of particular importance and the momentary position of engine development is not seldom dependent upon the development of both of the components, The piston ring is a well-known component and has been used in its present shape in the steam engine of the last century, Corresponding to its importance, the piston ring has been a rich field for creative activity and it is noteworthy that in spite of this the ring has maintained its shape through the many years. From the many and complicated designs which have been suggested as a packing between piston and cylinder wall hardly one suggestion has remained which does not resemble the original design of cast iron rectangular ring.

  6. Stacked Corrugated Horn Rings

    NASA Technical Reports Server (NTRS)

    Sosnowski, John B.

    2010-01-01

    This Brief describes a method of machining and assembly when the depth of corrugations far exceeds the width and conventional machining is not practical. The horn is divided into easily machined, individual rings with shoulders to control the depth. In this specific instance, each of the corrugations is identical in profile, and only differs in diameter and outer profile. The horn is segmented into rings that are cut with an interference fit (zero clearance with all machining errors biased toward contact). The interference faces can be cut with a reverse taper to increase the holding strength of the joint. The taper is a compromise between the interference fit and the clearance of the two faces during assembly. Each internal ring is dipped in liquid nitrogen, then nested in the previous, larger ring. The ring is rotated in the nest until the temperature of the two parts equalizes and the pieces lock together. The resulting assay is stable, strong, and has an internal finish that cannot be achieved through other methods.

  7. Resonance splitting in gyrotropic ring resonators.

    PubMed

    Jalas, Dirk; Petrov, Alexander; Krause, Michael; Hampe, Jan; Eich, Manfred

    2010-10-15

    We present the theoretical concept of an optical isolator based on resonance splitting in a silicon ring resonator covered with a magneto-optical polymer cladding. For this task, a perturbation method is derived for the modes in the cylindrical coordinate system. A polymer magneto-optical cladding causing a 0.01 amplitude of the off-diagonal element of the dielectric tensor is assumed. It is shown that the derived resonance splitting of the clockwise and counterclockwise modes increases for smaller ring radii. For the ring with a radius of approximately 1.5μm, a 29GHz splitting is demonstrated. An integrated optical isolator with a 10μm geometrical footprint is proposed based on a critically coupled ring resonator.

  8. Low thermal expansion seal ring support

    DOEpatents

    Dewis, David W.; Glezer, Boris

    2000-01-01

    Today, the trend is to increase the temperature of operation of gas turbine engines. To cool the components with compressor discharge air, robs air which could otherwise be used for combustion and creates a less efficient gas turbine engine. The present low thermal expansion sealing ring support system reduces the quantity of cooling air required while maintaining life and longevity of the components. Additionally, the low thermal expansion sealing ring reduces the clearance "C","C'" demanded between the interface between the sealing surface and the tip of the plurality of turbine blades. The sealing ring is supported by a plurality of support members in a manner in which the sealing ring and the plurality of support members independently expand and contract relative to each other and to other gas turbine engine components.

  9. GRISM Spectophotometry of the Uranus Ring

    NASA Astrophysics Data System (ADS)

    Smith, Bradford

    1997-07-01

    Details of the near-infrared spectral reflectance of the Uranus rings are poorly known, because of problems associated with the scattered light from the planet. Grism spectroscopy of the brightest part of the Epsilon ring will be made with the planet just outside the field of view. To minimize the glare from Uranus, the observations should made when the widest part of the Epsilon ring is at a position angle of approximately 174 degrees. This is one in a series of observations designed to intercompare the near-infrared spectral reflectivity of dark objects in the solar system. Some record of processes that occurred within the Uranus subnebula may be left on the surfaces of the ring particles or the surface coatings of the associated dark inner satellites.

  10. Deployable Fresnel Rings

    NASA Technical Reports Server (NTRS)

    Kennedy, Timothy F.; Fink, Patrick W.; Chu, Andrew W.; Lin, Gregory Y.

    2014-01-01

    Deployable Fresnel rings (DFRs) significantly enhance the realizable gain of an antenna. This innovation is intended to be used in combination with another antenna element, as the DFR itself acts as a focusing or microwave lens element for a primary antenna. This method is completely passive, and is also completely wireless in that it requires neither a cable, nor a connector from the antenna port of the primary antenna to the DFR. The technology improves upon the previous NASA technology called a Tri-Sector Deployable Array Antenna in at least three critical aspects. In contrast to the previous technology, this innovation requires no connector, cable, or other physical interface to the primary communication radio or sensor device. The achievable improvement in terms of antenna gain is significantly higher than has been achieved with the previous technology. Also, where previous embodiments of the Tri-Sector antenna have been constructed with combinations of conventional (e.g., printed circuit board) and conductive fabric materials, this innovation is realized using only conductive and non-conductive fabric (i.e., "e-textile") materials, with the possible exception of a spring-like deployment ring. Conceptually, a DFR operates by canceling the out-of-phase radiation at a plane by insertion of a conducting ring or rings of a specific size and distance from the source antenna, defined by Fresnel zones. Design of DFRs follow similar procedures to those outlined for conventional Fresnel zone rings. Gain enhancement using a single ring is verified experimentally and through computational simulation. The experimental test setup involves a microstrip patch antenna that is directly behind a single-ring DFR and is radiating towards a second microstrip patch antenna. The first patch antenna and DFR are shown. At 2.42 GHz, the DFR improves the transmit antenna gain by 8.6 dB, as shown in Figure 2, relative to the wireless link without the DFR. A figure illustrates the

  11. Rings dominate western Gulf

    NASA Astrophysics Data System (ADS)

    Vidal L., Francisco V.; Vidal L., Victor M. V.; Molero, José María Pérez

    Surface and deep circulation of the central and western Gulf of Mexico is controlled by interactions of rings of water pinched from the gulf's Loop Current. The discovery was made by Mexican oceanographers who are preparing a full-color, 8-volume oceanographic atlas of the gulf.Anticyclonic warm-core rings pinch off the Loop Current at a rate of about one to two per year, the scientists of the Grupo de Estudios Oceanográficos of the Instituto de Investigaciones Eléctricas (GEO-IIE) found. The rings migrate west until they collide with the continental shelf break of the western gulf, almost always between 22° and 23°N latitude. On their westward travel they transfer angular momentum and vorticity to the surrounding water, generating cyclonic circulations and vortex pairs that completely dominate the entire surface and deep circulation of the central and western gulf.

  12. Glassy dynamics of nanoparticles in semiflexible ring polymer nanocomposite melts

    PubMed Central

    Zhou, Xiaolin; Jiang, Yangwei; Deng, Zhenyu; Zhang, Linxi

    2017-01-01

    By employing molecular dynamics simulations, we explore the dynamics of NPs in semiflexible ring polymer nanocomposite melts. A novel glass transition is observed for NPs in semiflexible ring polymer melts as the bending energy (Kb) of ring polymers increases. For NPs in flexible ring polymer melts (Kb = 0), NPs move in the classic diffusive behavior. However, for NPs in semiflexible ring polymer melts with large bending energy, NPs diffuse very slowly and exhibit the glassy state in which the NPs are all irreversibly caged be the neighbouring semiflexible ring polymers. This glass transition occurs well above the classical glass transition temperature at which microscopic mobility is lost, and the topological interactions of semiflexible ring polymers play an important role in this non-classical glass transition. This investigation can help us understand the nature of the glass transition in polymer systems. PMID:28290546

  13. Glassy dynamics of nanoparticles in semiflexible ring polymer nanocomposite melts

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaolin; Jiang, Yangwei; Deng, Zhenyu; Zhang, Linxi

    2017-03-01

    By employing molecular dynamics simulations, we explore the dynamics of NPs in semiflexible ring polymer nanocomposite melts. A novel glass transition is observed for NPs in semiflexible ring polymer melts as the bending energy (Kb) of ring polymers increases. For NPs in flexible ring polymer melts (Kb = 0), NPs move in the classic diffusive behavior. However, for NPs in semiflexible ring polymer melts with large bending energy, NPs diffuse very slowly and exhibit the glassy state in which the NPs are all irreversibly caged be the neighbouring semiflexible ring polymers. This glass transition occurs well above the classical glass transition temperature at which microscopic mobility is lost, and the topological interactions of semiflexible ring polymers play an important role in this non-classical glass transition. This investigation can help us understand the nature of the glass transition in polymer systems.

  14. Ring laser gyroscope anode

    SciTech Connect

    Ljung, B.H.

    1981-03-17

    An anode for a ring laser gyroscope which provides improved current stability in the glow discharge path is disclosed. The anode of this invention permits operation at lower currents thereby allowing a reduction of heat dissipation in the ring laser gyroscope. The anode of one embodiment of this invention is characterized by a thumbtack appearance with a spherical end where the normal sharp end of the thumbtack would be located. The stem of the anode extends from the outside of the gyroscope structure to the interior of the structure such that the spherical end is substantially adjacent to the laser beam.

  15. GUARD RING SEMICONDUCTOR JUNCTION

    DOEpatents

    Goulding, F.S.; Hansen, W.L.

    1963-12-01

    A semiconductor diode having a very low noise characteristic when used under reverse bias is described. Surface leakage currents, which in conventional diodes greatly contribute to noise, are prevented from mixing with the desired signal currents. A p-n junction is formed with a thin layer of heavily doped semiconductor material disposed on a lightly doped, physically thick base material. An annular groove cuts through the thin layer and into the base for a short distance, dividing the thin layer into a peripheral guard ring that encircles the central region. Noise signal currents are shunted through the guard ring, leaving the central region free from such currents. (AEC)

  16. Unidirectional ring lasers

    DOEpatents

    Hohimer, J.P.; Craft, D.C.

    1994-09-20

    Unidirectional ring lasers formed by integrating nonreciprocal optical elements into the resonant ring cavity is disclosed. These optical elements either attenuate light traveling in a nonpreferred direction or amplify light traveling in a preferred direction. In one preferred embodiment the resonant cavity takes the form of a circle with an S-shaped crossover waveguide connected to two points on the interior of the cavity such that light traveling in a nonpreferred direction is diverted from the cavity into the crossover waveguide and reinjected out of the other end of the crossover waveguide into the cavity as light traveling in the preferred direction. 21 figs.

  17. Unidirectional ring lasers

    DOEpatents

    Hohimer, John P.; Craft, David C.

    1994-01-01

    Unidirectional ring lasers formed by integrating nonreciprocal optical elements into the resonant ring cavity. These optical elements either attenuate light traveling in a nonpreferred direction or amplify light traveling in a preferred direction. In one preferred embodiment the resonant cavity takes the form of a circle with an S-shaped crossover waveguide connected to two points on the interior of the cavity such that light traveling in a nonpreferred direction is diverted from the cavity into the crossover waveguide and reinjected out of the other end of the crossover waveguide into the cavity as light traveling in the preferred direction.

  18. The Secular Evolution of a Close Ring-Satellite System: The Excitation of Spiral Density Waves at a Nearby Gap Edge

    NASA Astrophysics Data System (ADS)

    Hahn, Joseph M.

    2008-06-01

    The Lagrange planetary equations are used to study secular evolution of a small, eccentric satellite that orbits within a narrow gap in a broad, self-gravitating planetary ring. These equations show that the satellite's secular perturbations of the ring will excite a very long wavelength spiral density wave that propagates away from the gap's outer edge. The amplitude of these waves, as well as their dispersion relation, are derived here. That dispersion relation reveals that a planetary ring can sustain two types of density waves: long waves that, in Saturn's A ring, would have wavelengths of λ ~ O(100) km and short waves that tend to be very nonlinear and are expected to quickly damp. The excitation of these waves also transports angular momentum from the ring to the satellite in a way that damps the satellite's eccentricity e, which also tends to reduce the amplitude of subsequent waves. The rate of eccentricity damping due to this wave action is then compared to the rates at which the satellite's Lindblad and corotation resonances alter the satellite's e. These results are then applied to the gap-embedded Saturnian satellites Pan and Daphnis, and the long-term stability of their eccentricities is assessed.

  19. In-Situ Dust Measurements in Jupiter's Gossamer Rings

    NASA Astrophysics Data System (ADS)

    Krueger, H.; Gruen, E.; Hamilton, D. P.

    2003-04-01

    Jupiter's ring system -- the archetype of ethereal ring systems -- consists of at least three components: the main ring, the vertically extended halo and the gossamer ring(s). The small moonlets Thebe and Amalthea orbit Jupiter within the gossamer ring region and structure in the intensity obtained from imaging observations indicates that these moons are the dominant sources of the gossamer ring material. The current picture implies that particles ejected from a source moon evolve inward under the Poynting-Robertson drag. Beyond Thebe's orbit, a very faint outward extension of the gossamer ring has also been observed which is not yet explained. Typical grain radii derived from optical imaging are a few micrometers. In November 2002 the Galileo spacecraft traversed the gossamer ring for the first time and had a close flyby at Amalthea. With the in-situ dust detector on board, dust measurements were collected throughout the gossamer ring and close to Amalthea. Several hundred impacts of dust grains were recorded and the data sets (impact charges, rise times, impact directions, etc.) of about 70 impacts were transmitted to Earth. In-situ dust measurements provide information about the physical properties of the dust environment not accessible with imaging techniques. They directly provide dust spatial densities along the spacecraft trajectory as well as grain sizes and impact speeds. This allows to test and refine current models of ring particle dynamics (see D. P. Hamilton et al., this conference). In particular, the direct measurement of grain sizes and dust spatial density in different regions of the gossamer ring allow to better constrain the forces dominating the grains' dynamics. The Galileo measurements in Jupiter's gossamer ring pave the way towards the in-situ dust measurements with Cassini in Saturn's E ring beginning in 2004.

  20. Galileo in-situ dust measurements in Jupiter's Gossamer Rings

    NASA Astrophysics Data System (ADS)

    Krueger, H.; Grün, E.; Hamilton, D. P.

    2003-05-01

    Jupiter's ring system -- the archetype of ethereal ring systems -- consists of at least three components: the main ring, the vertically extended halo and the gossamer ring(s). The small moonlets Thebe and Amalthea orbit Jupiter within the gossamer ring region and structure in the intensity obtained from imaging observations indicates that these moons are the dominant sources of the gossamer ring material. The current picture implies that particles ejected from a source moon evolve inward under the Poynting-Robertson drag. Beyond Thebe's orbit, a very faint outward extension of the gossamer ring has also been observed which is not yet explained. Typical grain radii derived from optical imaging are a few micrometers. In November 2002 the Galileo spacecraft traversed the gossamer ring for the first time and had a close flyby at Amalthea. With the in-situ dust detector on board, dust measurements were collected throughout the gossamer ring and close to Amalthea. Several hundred impacts of dust grains were recorded and the data sets (impact charges, rise times, impact directions, etc.) of about 90 impacts were transmitted to Earth. In-situ dust measurements provide information about the physical properties of the dust environment not accessible with imaging techniques. They directly provide dust spatial densities along the spacecraft trajectory as well as grain sizes and impact speeds. This allows to test and refine current models of ring particle dynamics (see D. P. Hamilton et al., this conference). In particular, the direct measurement of grain sizes and dust spatial density in different regions of the gossamer ring allow to better constrain the forces dominating the grains' dynamics. The Galileo measurements in Jupiter's gossamer ring pave the way towards the in-situ dust measurements with Cassini in Saturn's E ring beginning in 2004.

  1. Quantifying regional cerebral blood flow by N-isopropyl-P-[I-123]iodoamphetamine (IMP) using a ring type single-photon emission computed tomography system

    SciTech Connect

    Takahashi, N.; Odano, I.; Ohkubo, M.

    1994-05-01

    We developed a more accurate quantitative measurement of regional cerebral blood flow (rCBF) with the microsphere model using N-isopropyl-p-[I-123] iodoamphetamine (IMP) and a ring type single photon emission computed tomography (SPECT) system. SPECT studies were performed in 17 patients with brain diseases. A dose of 222 MBq (6 mCi) of [I-123]IMP was injected i.v., at the same time a 5 min period of arterial blood withdrawal was begun. SPECT data were acquired from 25 min to 60 min after tracer injection. For obtaining the brain activity concentration at 5 min after IMP injection, total brain counts collections and one minute period short time SPECT studies were performed at 5, 20, and 60 min. Measurement of the values of rCBF was calculated using short time SPECT images at 5 min (rCBF), static SPECT images corrected with total cerebral counts (rCBF{sub Ct}.) and those corrected with reconstructed counts on short time SPECT images (rCBF{sub Cb}). There was a good relationship (r=0.69) between rCBF and rCBF{sub Ct}, however, rCBF{sub Ct} tends to be underestimated in high flow areas and overestimated in low flow areas. There was better relationship between rCBF and rCBF{sub Cb}(r=0.92). The overestimation and underestimation shown in rCBF{sub Ct} was considered to be due to the correction of reconstructed counts using a total cerebral time activity curve, because of the kinetic behavior of [I-123]IMP was different in each region. We concluded that more accurate rCBF values could be obtained using the regional time activity curves.

  2. Ring Flame Stabilizer

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The Ring Flame Stabilizer has been developed in conjunction with Lewis Research Center. This device can lower pollutant emissions (which contribute to smog and air pollution) from natural-gas appliances such as furnaces and water heaters by 90 percent while improving energy efficiency by 2 percent.

  3. Ring of Stellar Death

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This false-color image from NASA's Spitzer Space Telescope shows a dying star (center) surrounded by a cloud of glowing gas and dust. Thanks to Spitzer's dust-piercing infrared eyes, the new image also highlights a never-before-seen feature -- a giant ring of material (red) slightly offset from the cloud's core. This clumpy ring consists of material that was expelled from the aging star.

    The star and its cloud halo constitute a 'planetary nebula' called NGC 246. When a star like our own Sun begins to run out of fuel, its core shrinks and heats up, boiling off the star's outer layers. Leftover material shoots outward, expanding in shells around the star. This ejected material is then bombarded with ultraviolet light from the central star's fiery surface, producing huge, glowing clouds -- planetary nebulas -- that look like giant jellyfish in space.

    In this image, the expelled gases appear green, and the ring of expelled material appears red. Astronomers believe the ring is likely made of hydrogen molecules that were ejected from the star in the form of atoms, then cooled to make hydrogen pairs. The new data will help explain how planetary nebulas take shape, and how they nourish future generations of stars.

    This image composite was taken on Dec. 6, 2003, by Spitzer's infrared array camera, and is composed of images obtained at four wavelengths: 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8 microns (red).

  4. Exotic damping ring lattices

    SciTech Connect

    Palmer, R.B.

    1987-05-01

    This paper looks at, and compares three types of damping ring lattices: conventional, wiggler lattice with finite ..cap alpha.., wiggler lattice with ..cap alpha.. = 0, and observes the attainable equilibrium emittances for the three cases assuming a constraint on the attainable longitudinal impedance of 0.2 ohms. The emittance obtained are roughly in the ratio 4:2:1 for these cases.

  5. Ring laser scatterometer

    DOEpatents

    Ackermann, Mark; Diels, Jean-Claude

    2005-06-28

    A scatterometer utilizes the dead zone resulting from lockup caused by scatter from a sample located in the optical path of a ring laser at a location where counter-rotating pulses cross. The frequency of one pulse relative to the other is varied across the lockup dead zone.

  6. Reading, Writing, and Rings!

    ERIC Educational Resources Information Center

    Aschbacher, Pamela; Li, Erika; Hammon, Art

    2008-01-01

    "Reading, Writing, and Rings!" was created by a team of elementary teachers, literacy experts, and scientists in order to integrate science and literacy. These free units bring students inside NASA's Cassini-Huygens mission to Saturn. The authors--a science teacher and education outreach specialist and two evaluators of educational programs--have…

  7. Making Molecular Borromean Rings

    ERIC Educational Resources Information Center

    Pentecost, Cari D.; Tangchaivang, Nichol; Cantrill, Stuart J.; Chichak, Kelly S.; Peters, Andrea J.; Stoddart, Fraser J.

    2007-01-01

    A procedure that requires seven 4-hour blocks of time to allow undergraduate students to prepare the molecular Borromean rings (BRs) on a gram-scale in 90% yield is described. The experiment would serve as a nice capstone project to culminate any comprehensive organic laboratory course and expose students to fundamental concepts, symmetry point…

  8. Dust Sources of Saturn's E Ring

    NASA Astrophysics Data System (ADS)

    Spahn, F.; Schmidt, J.; Albers, N.; Kempf, S.; Krivov, A. V.; Sremcevic, M.

    The recent detection of a dust plume at Enceladus' south pole sheds new light on the origin of the E ring of Saturn. The particles probably condense from gas vents escaping from a system of cracks covering the south pole that appears unusually hot in the Cassini infrared experiments. The main fraction of the E ring dust is created in these gas vents. Still, significant amounts of dust should originate from grains ejected by hypervelocity impacts of E ring particles (ERPs), or alternatively, of interplanetary dust grains (IDPs) on the Saturnian moons embedded in the E ring. We estimate the contributions of impactor -ejecta created dust at these various satellites in the ring, relative to the production rate of grains in the plume at Enceladus. Furthermore, we compare the amount of dust created by both projectile families - ERPs and IDPs - and predict that one can clearly discriminate between the ejecta raised by either projectile families in the data of the Cassini dust detector (CDA) collected at close flybys with the moons embedded in the E ring.

  9. UVIS ring occultations show F ring feature location and optical depth correlated with Prometheus

    NASA Astrophysics Data System (ADS)

    Meinke, Bonnie K.; Esposito, L. W.; Albers, N.

    2010-05-01

    We find 24 statistically significant features in the F ring occultations using the High Speed Photometer (HSP) channel of the Cassini Ultraviolet Imaging Spectrograph (UVIS). These features are likely transient clumps of material embedded in the ring, each of which attenuates stellar signal during an occultation because the ring material is more densely packed at that location. In fact, two of these features are opaque, indicating they may be solid moonlets. Two trends are evident in the azimuthal location of these 24 F ring features with respect to that of Prometheus. First, the orbital locations of these features are mostly opposite Prometheus, as 11 of the 24 occupy the orbital region separated from Prometheus by 180° ± 20°. Second, average feature optical depth is maximum near the antipode of Prometheus in orbit. Our hypothesis is that these results show aggregation and disaggregation of clumps after Prometheus passes by. As Prometheus passes interior to the F ring, it encounters material once every synodic period, 68 days. Optical depth indicates density of ring material along the line of sight, so as material clumps together, we expect to see higher optical depths. Thus we infer that the encounter stimulates clumping of material that reaches a maximum 180° downstream. This may reinforce similar evidence that Ring-Moon interaction stimulates clumping in the F ring region from Cassini imaging (Beurle, et al., 2010) and at the B ring edge (Esposito, et al., 2010). Esposito, et al. (2010) suggest that the combined mass and velocity evolution of the ring system resembles a predator/prey model. This research was supported by the Cassini Project.

  10. Prometheus Induced Vorticity in Saturn's F Ring

    NASA Astrophysics Data System (ADS)

    Sutton, Phil J.; Kusmartsev, Feo V.

    2016-11-01

    Saturn's rings are known to show remarkable real time variability in their structure. Many of which can be associated to interactions with nearby moons and moonlets. Possibly the most interesting and dynamic place in the rings, probably in the whole Solar System, is the F ring. A highly disrupted ring with large asymmetries both radially and azimuthally. Numerically non-zero components to the curl of the velocity vector field (vorticity) in the perturbed area of the F ring post encounter are witnessed, significantly above the background vorticity. Within the perturbed area rich distributions of local rotations is seen located in and around the channel edges. The gravitational scattering of ring particles during the encounter causes a significant elevated curl of the vector field above the background F ring vorticity for the first 1-3 orbital periods post encounter. After 3 orbital periods vorticity reverts quite quickly to near background levels. This new found dynamical vortex life of the ring will be of great interest to planet and planetesimals in proto-planetary disks where vortices and turbulence are suspected of having a significant role in their formation and migrations. Additionally, it is found that the immediate channel edges created by the close passage of Prometheus actually show high radial dispersions in the order 20-50 cm/s, up to a maximum of 1 m/s. This is much greater than the value required by Toomre for a disk to be unstable to the growth of axisymmetric oscillations. However, an area a few hundred km away from the edge shows a more promising location for the growth of coherent objects.

  11. Ring Bubbles of Dolphins

    NASA Technical Reports Server (NTRS)

    Shariff, Karim; Marten, Ken; Psarakos, Suchi; White, Don J.; Merriam, Marshal (Technical Monitor)

    1996-01-01

    The article discusses how dolphins create and play with three types of air-filled vortices. The underlying physics is discussed. Photographs and sketches illustrating the dolphin's actions and physics are presented. The dolphins engage in this behavior on their own initiative without food reward. These behaviors are done repeatedly and with singleminded effort. The first type is the ejection of bubbles which, after some practice on the part of the dolphin, turn into toroidal vortex ring bubbles by the mechanism of baroclinic torque. These bubbles grow in radius and become thinner as they rise vertically to the surface. One dolphin would blow two in succession and guide them to fuse into one. Physicists call this a vortex reconnection. In the second type, the dolphins first create an invisible vortex ring in the water by swimming on their side and waving their tail fin (also called flukes) vigorously. This vortex ring travels horizontally in the water. The dolphin then turns around, finds the vortex and injects a stream of air into it from its blowhole. The air "fills-out" the core of the vortex ring. Often, the dolphin would knock-off a smaller ring bubble from the larger ring (this also involves vortex reconnection) and steer the smaller ring around the tank. One other dolphin employed a few other techniques for planting air into the fluke vortex. One technique included standing vertically in the water with tail-up, head-down and tail piercing the free surface. As the fluke is waved to create the vortex ring, air is entrained from above the surface. Another technique was gulping air in the mouth, diving down, releasing air bubbles from the mouth and curling them into a ring when they rose to the level of the fluke. In the third type, demonstrated by only one dolphin, the longitudinal vortex created by the dorsal fin on the back is used to produce 10-15 foot long helical bubbles. In one technique she swims in a curved path. This creates a dorsal fin vortex since

  12. Aromaticity-controlled thermal stability of photochromic systems based on a six-membered ring as ethene bridges: photochemical and kinetic studies.

    PubMed

    Yang, Yuheng; Xie, Yongshu; Zhang, Qiong; Nakatani, Keitaro; Tian, He; Zhu, Weihong

    2012-09-10

    Three photochromic compounds--2-butyl-5,6-bis[5-(4-methoxyphenyl)-2-methylthiophen-3-yl]-1 H-benzo[de]isoquinoline-1,3(2 H)-dione (BTE-NA), 4,5-bis[5-(4-methoxyphenyl)-2-methylthiophen-3-yl]benzo[c][1,2,5]thiadiazole (BTA), and BTTA, which contain naphthalimide, benzothiadiazole, and benzobisthiadiazole as six-membered ethene bridges with different aromaticities--were systematically studied in solution, sol-gel, and single-crystal states. They exhibit typical photochromic performance with considerably high cyclization quantum yields. BTE-NA, BTA, and BTTA form a typical donor-π-acceptor (D-π-A) system with significant intramolecular charge transfer (ICT) between HOMO and LUMO upon excitation, thus realizing the fluorescence modulation by both photochromism and solvatochromism. The three ethene bridges with different degrees of aromaticity can provide a systematic comparison of the thermal stability evolution for their corresponding closed forms (c-BTE-NA, c-BTA, and c-BTTA). c-BTE-NA shows first-order decay in various solvents from cyclohexane to acetonitrile. c-BTA only shows first-order decay in polar solvents such as chloroform, whereas it is stable in nonpolar solvents like toluene. In contrast, the less aromatic property of BTTA gives rise to its unprecedented thermal stability in various solvents even at elevated temperatures in toluene (328 K). Moreover, the small energy barrier between the parallel and antiparallel conformers allows the full conversion from BTTA to c-BTTA. In well-ordered crystal states, all three compounds adopt a parallel conformation. Interestingly, BTTA forms a twin crystal of asymmetric nature with interactions between the electron-rich oxygen atom of the methoxy group and the carbon atom of the electron-deficient benzobisthiadiazole moiety. This work contributes to the understanding of aromaticity-controlled thermal stability of photochromic systems based on a six-membered ring as an ethene bridge, and a broadening of the

  13. Reinterpreting the Sharp Edges of Planetary Rings

    NASA Astrophysics Data System (ADS)

    Rimlinger, Thomas; Hamilton, Douglas P.; Hahn, Joseph M.

    2016-10-01

    Narrow ringlets are found throughout the Solar System and are typically 1-100 km wide. Angular momentum, L, is the key to understanding how narrow rings remain confined; L2 ∝ a(1 - e2) for semimajor axis a and eccentricity e. In a circular ring, L conservation demands that the ring quickly spread apart when some colliding particles lose energy while others gain it. By contrast, in an eccentric ring, energy loss and the associated decay of the average semi-major axes can be offset by a decrease in the average eccentricity. We argue that a ring's lifetime can be greatly extended if particles arrange themselves in this way (Borderies et al. 1984). The key difference of our model, however, is that rings need not be shepherded and can confine themselves provided they are sufficiently eccentric. Satellites merely extend the rings' lifespans by pumping up their eccentricities.This confinement mechanism can explain the existence and longevity of narrow ringlets in a variety of contexts. Saturn's Titan ringlet, which is quite circular, may nevertheless be able to confine itself indefinitely if its eccentricity decay is balanced by the increase from the resonance with Titan. Preliminary simulations presented by Rimlinger et al. at this year's DDA Conference have verified that this ring can self-confine even in the absence of any satellite; we update these findings with new results that include the effects of Titan. Furthermore, Mimas' resonance with the edge of the B ring may excite its higher order modes to similar effect. We update the findings of Hahn and Spitale (2013), who used artificial forces to confine the B ring's edge, and suggest that with a suitable viscosity and density, no such forces will be needed to keep the edge sharp. Finally, a ring that is "born" with a sufficiently high eccentricity may live for hundreds of millions or even billions of years in isolation if the rate of decay is slow enough. We present simulations exploring such a scenario.

  14. Of Rings and Volcanoes

    NASA Astrophysics Data System (ADS)

    2002-01-01

    Office National d'Etudes et de Recherches Aérospatiales (ONERA) , Laboratoire d'Astrophysique de Grenoble (LAOG) and the DESPA and DASGAL laboratories of the Observatoire de Paris in France, in collaboration with ESO. The CONICA infra-red camera was built, under an ESO contract, by the Max-Planck-Institut für Astronomie (MPIA) (Heidelberg) and the Max-Planck Institut für Extraterrestrische Physik (MPE) (Garching) in Germany, in collaboration with ESO. Saturn - Lord of the rings ESO PR Photo 04a/02 ESO PR Photo 04a/02 [Preview - JPEG: 460 x 400 pix - 54k] [Normal - JPEG: 1034 x 800 pix - 200k] Caption : PR Photo 04a/02 shows the giant planet Saturn, as observed with the VLT NAOS-CONICA Adaptive Optics instrument on December 8, 2001; the distance was 1209 million km. It is a composite of exposures in two near-infrared wavebands (H and K) and displays well the intricate, banded structure of the planetary atmosphere and the rings. Note also the dark spot at the south pole at the bottom of the image. One of the moons, Tethys, is visible as a small point of light below the planet. It was used to guide the telescope and to perform the adaptive optics "refocussing" for this observation. More details in the text. Technical information about this photo is available below. This NAOS/CONICA image of Saturn ( PR Photo 04a/02 ), the second-largest planet in the solar system, was obtained at a time when Saturn was close to summer solstice in the southern hemisphere. At this moment, the tilt of the rings was about as large as it can be, allowing the best possible view of the planet's South Pole. That area was on Saturn's night side in 1982 and could therefore not be photographed during the Voyager encounter. The dark spot close to the South Pole is a remarkable structure that measures approximately 300 km across. It was only recently observed in visible light from the ground with a telescope at the Pic du Midi Observatory in the Pyrenees (France) - this is the first infrared image to

  15. Inorganic glass ceramic slip rings

    NASA Technical Reports Server (NTRS)

    Glossbrenner, E. W.; Cole, S. R.

    1972-01-01

    Prototypes of slip rings have been fabricated from ceramic glass, a material which is highly resistant to deterioration due to high temperature. Slip ring assemblies were not structurally damaged by mechanical tests and performed statisfactorily for 200 hours.

  16. Less invasive lumbopelvic fixation technique using a percutaneous pedicle screw system for unstable pelvic ring fracture in a patient with severe multiple traumas.

    PubMed

    Yano, Sei; Aoki, Yasuchika; Watanabe, Atsuya; Nakajima, Takayuki; Takazawa, Makoto; Hirasawa, Hiroyuki; Takahashi, Kazuhisa; Nakagawa, Koichi; Nakajima, Arata; Takahashi, Hiroshi; Orita, Sumihisa; Eguchi, Yawara; Suzuki, Takane; Ohtori, Seiji

    2017-02-01

    Pelvic ring fractures are defined as life-threatening injuries that can be treated surgically with external or internal fixation. The authors report on an 81-year-old woman with an unstable pelvic fracture accompanying multiple traumas that was successfully treated with a less invasive procedure. The patient was injured in a traffic accident and sustained a total of 20 fractures, including pelvic ring, bilateral rib, and lumbar transverse processes fractures, and multiple fractures of both upper and lower extremities. The pelvic ring fracture was unstable with fractures of the bilateral sacrum with right sacroiliac disruption, right superior and inferior pubic rami, left superior pubic ramus, and ischium. During emergency surgery, bilateral external fixation was applied to the iliac crest to stabilize the pelvic ring. Second and third surgeries were performed 11 and 18 days after the first emergency surgery, respectively, to treat the multiple fractures. At the third surgery, the pelvic ring fracture was stabilized surgically using a less invasive posterior fixation technique. In this technique, 2 iliac screws were inserted on each side following an 8-cm midline posterior incision from the S-1 to S-3 spinous process, with the subcutaneous tissue detached from the fascia of the paraspinal muscles. The S-2 spinous process was removed and 2 rods were connected to bilateral iliac screws to stabilize the bilateral ilium in a switchback fashion. A crosslink device was applied to connect the 2 rods at the base of the S-2 spinous process. Following pelvic fixation, percutaneous pedicle screws were inserted into L-4 and L-5 vertebral bodies on both sides, and connected to the cranial rod connecting the bilateral iliac screws, thus completing the lumbopelvic fixation. The postoperative course was favorable with no postoperative complications. At the 10-month follow-up, bone union had been achieved at the superior ramus of the pubis, the patient did not complain of pain, and

  17. Electronic properties of superlattices on quantum rings

    NASA Astrophysics Data System (ADS)

    da Costa, D. R.; Chaves, A.; Ferreira, W. P.; Farias, G. A.; Ferreira, R.

    2017-04-01

    We present a theoretical study of the one-electron states of a semiconductor-made quantum ring (QR) containing a series of piecewise-constant wells and barriers distributed along the ring circumference. The single quantum well and the superlattice cases are considered in detail. We also investigate how such confining potentials affect the Aharonov–Bohm like oscillations of the energy spectrum and current in the presence of a magnetic field. The model is simple enough so as to allow obtaining various analytical or quasi-analytical results. We show that the well-in-a-ring structure presents enhanced localization features, as well as specific geometrical resonances in its above-barrier spectrum. We stress that the superlattice-in-a-ring structure allows giving a physical meaning to the often used but usually artificial Born–von-Karman periodic conditions, and discuss in detail the formation of energy minibands and minigaps for the circumferential motion, as well as several properties of the superlattice eigenstates in the presence of the magnetic field. We obtain that the Aharonov–Bohm oscillations of below-barrier miniband states are reinforced, owing to the important tunnel coupling between neighbour wells of the superlattice, which permits the electron to move in the ring. Additionally, we analysis a superlattice-like structure made of a regular distribution of ionized impurities placed around the QR, a system that may implement the superlattice in a ring idea. Finally, we consider several random disorder models, in order to study roughness disorder and to tackle the robustness of some results against deviations from the ideally nanostructured ring system.

  18. Einstein Ring in Distant Universe

    NASA Astrophysics Data System (ADS)

    2005-06-01

    on the newly discovered Einstein ring. The image quality ("seeing") of the R-band image is exceptional (0.5") and the image reveals the lensing system in stunning details. The central dot is the lens, a quiescent massive galaxy that distort the light emitted by background sources. The large arc surrounding the central lens is a part of the Einstein-ring created by a background source finely aligned with the lens. The reddish colour indicates that the redshift of the system is very large. FORS2 spectroscopy of the lensing system yield a redshift close to 1 for the lens (we see the lens as it was when the universe was half its present size), and a record-breaking redshift z=3.8 for a background source of such brightness, hence we see the object (a star forming galaxy) as it was when the universe was only 12% of its present age. The lensing model indicates that the light of the source is magnified at least 13 times. The right panel shows the reconstructed image based on the model of the lens and the source, showing the ring to extend over 3/4 of a circle. "There are only a very few optical rings or arcs known, and even less so in which the lens and the source are at large distance, i.e. more than about 7,000 million light-years away (or half the present age of the Universe)", says Rémi Cabanac, former ESO Fellow and now working at the Canada-France-Hawaii Telescope. "Moreover, very few are nearly complete", he adds. But in the case of this newly found cosmic ring, the images show it to extend to almost 3/4 of a circle. The lensing galaxy is located at a distance of about 8,000 million light-years from us, while the source galaxy whose light is distorted, is much farther away, at 12,000 million light-years. Thus, we see this galaxy as it was when the universe was only 12% of its present age. The lens magnifies the source almost 13 times. The observations reveal the galaxy acting as a lens to be a rather quiet galaxy, 40,000 light-years wide, with an old stellar

  19. Galileo In-Situ Dust Measurements in Jupiter's Gossamer Rings

    NASA Astrophysics Data System (ADS)

    Krueger, H.; Hamilton, D. P.; Gruen, E.

    Jupiter's ring system consists of at least three components: the inner main ring, the vertically extended halo and the gossamer ring(s) further out. The small moons Thebe and Amalthea orbit Jupiter within the gossamer ring and are believed to be the sources of gossamer ring material. A very faint ring extension has also been observed beyond Thebe's orbit. On 5 November 2002 the Galileo spacecraft traversed Jupiter's gossamer ring system for the first time. High-resolution dust data were obtained with the dust detector on board down to 2.33 R_J , i.e. well inside Amalthea's orbit. A second ring passage occurred on 21 September 2003, a few hours before Galileo impacted Jupiter. This time, dust data were successfully received down to Amalthea's orbit at 2.5 R_J , however, with much reduced time-resolution. Several thousand dust impacts were counted during both ring passages, and the full data sets (impact charges, rise times, impact directions, etc.) of about 90 dust impacts were transmitted to Earth. In-situ dust measurements provide information about the physical properties of the dust environment not accessible with imaging techniques. They directly measure dust spatial densities along the spacecraft trajectory as well as grain sizes and impact speeds. Our as yet preliminary analysis %of the gossamer ring data implies particle sizes in the sub-micron and micron range. The size distribution -- increasing towards smaller particles -- is similar in the Thebe ring and the ring's outer extension, whereas in the Amalthea ring it is steeper. Dust number densities are about 104 - 106 km-3 . Our dust data allow for the first time to compare in-situ measurements with the results optical obtained from the inversion of optical images. It appears that small sub-micron grains dominate the number density whereas larger particles with at least a few micron radii contribute most to the optical depth. The dust density shows previously unrecognised fine-structure in the ring between

  20. The cryogenic storage ring CSR

    NASA Astrophysics Data System (ADS)

    von Hahn, R.; Becker, A.; Berg, F.; Blaum, K.; Breitenfeldt, C.; Fadil, H.; Fellenberger, F.; Froese, M.; George, S.; Göck, J.; Grieser, M.; Grussie, F.; Guerin, E. A.; Heber, O.; Herwig, P.; Karthein, J.; Krantz, C.; Kreckel, H.; Lange, M.; Laux, F.; Lohmann, S.; Menk, S.; Meyer, C.; Mishra, P. M.; Novotný, O.; O'Connor, A. P.; Orlov, D. A.; Rappaport, M. L.; Repnow, R.; Saurabh, S.; Schippers, S.; Schröter, C. D.; Schwalm, D.; Schweikhard, L.; Sieber, T.; Shornikov, A.; Spruck, K.; Sunil Kumar, S.; Ullrich, J.; Urbain, X.; Vogel, S.; Wilhelm, P.; Wolf, A.; Zajfman, D.

    2016-06-01

    An electrostatic cryogenic storage ring, CSR, for beams of anions and cations with up to 300 keV kinetic energy per unit charge has been designed, constructed, and put into operation. With a circumference of 35 m, the ion-beam vacuum chambers and all beam optics are in a cryostat and cooled by a closed-cycle liquid helium system. At temperatures as low as (5.5 ± 1) K inside the ring, storage time constants of several minutes up to almost an hour were observed for atomic and molecular, anion and cation beams at an energy of 60 keV. The ion-beam intensity, energy-dependent closed-orbit shifts (dispersion), and the focusing properties of the machine were studied by a system of capacitive pickups. The Schottky-noise spectrum of the stored ions revealed a broadening of the momentum distribution on a time scale of 1000 s. Photodetachment of stored anions was used in the beam lifetime measurements. The detachment rate by anion collisions with residual-gas molecules was found to be extremely low. A residual-gas density below 140 cm-3 is derived, equivalent to a room-temperature pressure below 10-14 mbar. Fast atomic, molecular, and cluster ion beams stored for long periods of time in a cryogenic environment will allow experiments on collision- and radiation-induced fragmentation processes of ions in known internal quantum states with merged and crossed photon and particle beams.

  1. The cryogenic storage ring CSR.

    PubMed

    von Hahn, R; Becker, A; Berg, F; Blaum, K; Breitenfeldt, C; Fadil, H; Fellenberger, F; Froese, M; George, S; Göck, J; Grieser, M; Grussie, F; Guerin, E A; Heber, O; Herwig, P; Karthein, J; Krantz, C; Kreckel, H; Lange, M; Laux, F; Lohmann, S; Menk, S; Meyer, C; Mishra, P M; Novotný, O; O'Connor, A P; Orlov, D A; Rappaport, M L; Repnow, R; Saurabh, S; Schippers, S; Schröter, C D; Schwalm, D; Schweikhard, L; Sieber, T; Shornikov, A; Spruck, K; Sunil Kumar, S; Ullrich, J; Urbain, X; Vogel, S; Wilhelm, P; Wolf, A; Zajfman, D

    2016-06-01

    An electrostatic cryogenic storage ring, CSR, for beams of anions and cations with up to 300 keV kinetic energy per unit charge has been designed, constructed, and put into operation. With a circumference of 35 m, the ion-beam vacuum chambers and all beam optics are in a cryostat and cooled by a closed-cycle liquid helium system. At temperatures as low as (5.5 ± 1) K inside the ring, storage time constants of several minutes up to almost an hour were observed for atomic and molecular, anion and cation beams at an energy of 60 keV. The ion-beam intensity, energy-dependent closed-orbit shifts (dispersion), and the focusing properties of the machine were studied by a system of capacitive pickups. The Schottky-noise spectrum of the stored ions revealed a broadening of the momentum distribution on a time scale of 1000 s. Photodetachment of stored anions was used in the beam lifetime measurements. The detachment rate by anion collisions with residual-gas molecules was found to be extremely low. A residual-gas density below 140 cm(-3) is derived, equivalent to a room-temperature pressure below 10(-14) mbar. Fast atomic, molecular, and cluster ion beams stored for long periods of time in a cryogenic environment will allow experiments on collision- and radiation-induced fragmentation processes of ions in known internal quantum states with merged and crossed photon and particle beams.

  2. Nonlinear dynamics aspects of modern storage rings

    SciTech Connect

    Helleman, R.H.G.; Kheifets, S.A.

    1986-01-01

    It is argued that the nonlinearity of storage rings becomes an essential problem as the design parameters of each new machine are pushed further and further. Yet the familiar methods of classical mechanics do not allow determination of single particle orbits over reasonable lengths of time. It is also argued that the single particle dynamics of a storage ring is possibly one of the cleanest and simplest nonlinear dynamical systems available with very few degrees of freedom. Hence, reasons are found for accelerator physicists to be interested in nonlinear dynamics and for researchers in nonlinear dynamics to be interested in modern storage rings. The more familiar methods of treating nonlinear systems routinely used in acclerator theory are discussed, pointing out some of their limitations and pitfalls. 39 refs., 1 fig. (LEW)

  3. RINGED ACCRETION DISKS: EQUILIBRIUM CONFIGURATIONS

    SciTech Connect

    Pugliese, D.; Stuchlík, Z. E-mail: zdenek.stuchlik@physics.cz

    2015-12-15

    We investigate a model of a ringed accretion disk, made up by several rings rotating around a supermassive Kerr black hole attractor. Each toroid of the ringed disk is governed by the general relativity hydrodynamic Boyer condition of equilibrium configurations of rotating perfect fluids. Properties of the tori can then be determined by an appropriately defined effective potential reflecting the background Kerr geometry and the centrifugal effects. The ringed disks could be created in various regimes during the evolution of matter configurations around supermassive black holes. Therefore, both corotating and counterrotating rings have to be considered as being a constituent of the ringed disk. We provide constraints on the model parameters for the existence and stability of various ringed configurations and discuss occurrence of accretion onto the Kerr black hole and possible launching of jets from the ringed disk. We demonstrate that various ringed disks can be characterized by a maximum number of rings. We present also a perturbation analysis based on evolution of the oscillating components of the ringed disk. The dynamics of the unstable phases of the ringed disk evolution seems to be promising in relation to high-energy phenomena demonstrated in active galactic nuclei.

  4. Ring closure in actin polymers

    NASA Astrophysics Data System (ADS)

    Sinha, Supurna; Chattopadhyay, Sebanti

    2017-03-01

    We present an analysis for the ring closure probability of semiflexible polymers within the pure bend Worm Like Chain (WLC) model. The ring closure probability predicted from our analysis can be tested against fluorescent actin cyclization experiments. We also discuss the effect of ring closure on bend angle fluctuations in actin polymers.

  5. DC-Powered Jumping Ring

    ERIC Educational Resources Information Center

    Jeffery, Rondo N.; Farhang, Amiri

    2016-01-01

    The classroom jumping ring demonstration is nearly always performed using alternating current (AC), in which the ring jumps or flies off the extended iron core when the switch is closed. The ring jumps higher when cooled with liquid nitrogen (LN2). We have performed experiments using DC to power the solenoid and find similarities and significant…

  6. Uranus: the rings are black.

    PubMed

    Sinton, W M

    1977-11-04

    An upper limit of 0.05 is established for the geometric albedo of the newly discovered rings of Uranus. In view of this very low albedo, the particles of the rings cannot be ice-covered as are those of rings A and B of Saturn.

  7. Satellite Rings Movie

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This brief movie clip (of which the release image is a still frame), taken by NASA's Cassini spacecraft as it approached Jupiter, shows the motions, over a 16 hour-period, of two satellites embedded in Jupiter's ring. The moon Adrastea is the fainter of the two, and Metis the brighter. Images such as these will be used to refine the orbits of the two bodies.

    The movie was made from images taken during a 40-hour sequence of the Jovian ring on December 11, 2000.

    Cassini is a cooperative mission of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages Cassini for NASA's Office of Space Science, Washington, D.C.

  8. Saturn's E, G, and F rings - Modulated by the plasma sheet?

    NASA Technical Reports Server (NTRS)

    Morfill, G. E.; Gruen, E.; Johnson, T. V.

    1983-01-01

    Saturn's broad E ring, the narrow G ring, and the structured and apparently time-variable F ring(s) contain many micron and submicron-sized particles, which make up the 'visible' component. These rings (or ring systems) are in direct contact with magnetospheric plasma. Fluctuations in the plasma density and/or mean energy, due to magnetospheric and solar wind processes, may induce stochastic charge variations on the dust particles, which in turn lead to an orbit perturbation and spatial diffusion. In addition, Coulomb drag forces may be important, in particular for the E ring. The possibility that electromagnetic effects may play a role in determining the F ring structure and its possible time variations is critically examined. Sputtering of micron-sized dust particles in the E ring by magnetospheric ions yields lifetimes of 100 to 10,000 years. This effect as well as the plasma induced transport processes require an active source for the E ring, probably Enceladus.

  9. Strained Ring Energetic Binders

    DTIC Science & Technology

    1993-08-27

    polyhomobenzvalene ( PHBV ). PHBV was not found to have the mechanical instability problems of PBV, but was still thermally unstable (Tonset - 660C, Tmax - 1090C...DISCUSSION 4 Polybenzvalene (PBV) 4 Polyhomobenzvalene ( PHBV ) 6 Chain-Transfer Studies 11 CONCLUSIONS 15 EXPERIMENTAL PROCEDURES 16 .F 4E 19 APPENDICES A...strained ring polymers similar to PBV are known. The investigation of one of these polymers, polyhomobenzvalene ( PHBV ), is also described in this report

  10. The impact of geocoronal density on ring current development

    NASA Astrophysics Data System (ADS)

    Ilie, R.; Skoug, R. M.; Funsten, H. O.; Liemohn, M. W.; Bailey, J. J.; Gruntman, M.

    2013-07-01

    Long-term ring current decay following a magnetic storm is mainly due to charge exchange collisions of ring current ions with geocoronal neutral atoms forming energetic neutral atoms (ENAs) that leave the ring current system. Therefore, the density distribution of these cold and tenuous neutral hydrogen atoms plays a key role in the ring current recovery. TWINS ENA images provide a direct measurement of these ENA losses and therefore insight into the dynamics of the ring current decay through interactions with the geocorona. To assess the influence of geocoronal neutrals on ring current decay, we compare the predicted ENA emission using five different geocoronal models and the HEIDI ring current model to simulate the July 22, 2009 storm. We show that for high energy H+ (≥100 keV), all geocoronal models predict similar decay rates of the ring current ions. However, for low energy ions (≤100 keV), the decay rate varies significantly depending on the geocoronal density model. Comparison with TWINS ENA images shows that the location of the peak ENA enhancements is highly dependent on the distribution of geocoronal hydrogen density. The ring current topology depends greatly on the hydrogen model used, therefore knowing the H-distribution is very important in understanding how the ring current recovers following a magnetic storm.

  11. Earth Rings for Planetary Environment Control

    NASA Astrophysics Data System (ADS)

    Pearson, Jerome; Oldson, John; Levin, Eugene; Carroll, Joseph

    2002-01-01

    For most of its past, large parts of the Earth have experienced subtropical climates, with high sea levels and no polar icecaps. This warmer environment was punctuated 570, 280, and 3 million years ago with periods of glaciation that covered temperate regions with thick ice for millions of years. At the end of the current ice age, a warmer climate could flood coastal cities, even without human-caused global warming. In addition, asteroids bombard the Earth periodically, with impacts large enough to destroy most life on Earth, and the sun is warming inexorably. This paper proposes a concept to solve these problems simultaneously, by creating an artificial planetary ring about the Earth to shade it. Past proposals for space climate control have depended on gigantic engineering structures launched from Earth and placed in Earth orbit or at the Earth-Sun L1 libration point, requiring fabrication, large launch masses and expense, constant control, and repair. Our solution is to begin by using lunar material, and then mine and remove Earth-orbit-crossing asteroids and discard the tailings into Earth orbit, to form a broad, flat ring like those of Saturn. This solution is evaluated and compared with other alternatives. Such ring systems can persist for thousands of years, and can be maintained by shepherding satellites or by continual replenishment from new asteroids to replace the edges of the ring lost by diffusion. An Earth ring at R = 1.3-1.83 RE would shade only the equatorial regions, moderating climate extremes, and could reverse a century of global warming. It could also absorb particles from the radiation belts, making trips to high Earth orbit and GEO safer for humans and for electronics. It would also light the night many times as bright as the full moon. A preliminary design of the ring is developed, including its location, mass, composition, stability, and timescale required. A one-dimensional climate model is used to evaluate the Earth ring performance

  12. The dark side of the rings of Uranus.

    PubMed

    de Pater, Imke; Hammel, H B; Showalter, Mark R; van Dam, Marcos A

    2007-09-28

    The rings of Uranus are oriented edge-on to Earth in 2007 for the first time since their 1977 discovery. This event provides a rare opportunity to observe their dark (unlit) side, where dense rings darken to near invisibility, but faint rings become much brighter. We present a ground-based infrared image of the unlit side of the rings that shows that the system has changed dramatically since previous views. A broad cloud of faint material permeates the system but is not correlated with the well-known narrow rings or with the embedded dust belts imaged by the Voyager spacecraft. Although some differences can be explained by the unusual viewing angle, we conclude that the dust distribution within the system has changed substantially since the 1986 Voyager encounter and that it occurs on much larger scales than has been seen in other planetary systems.

  13. Helmet latching and attaching ring

    NASA Technical Reports Server (NTRS)

    Chase, E. W.; Viikinsalo, S. J. (Inventor)

    1970-01-01

    A neck ring releasably secured to a pressurized garment carries an open-ended ring normally in the engagement position fitted into an annular groove and adapted to fit into a complementary annular groove formed in a helmet. Camming means formed on the inner surface at the end of the helmet engages the open-ended ring to retract the same and allow for one motion donning even when the garment is pressurized. A projection on the end of the split ring is engageable to physically retract the split ring.

  14. Slip ring experience in long duration space applications

    NASA Technical Reports Server (NTRS)

    Phinney, Damon D.

    1986-01-01

    Ball Aerospace experience with slip rings in space extends back to 1962. Over 40 multi-ring assemblies have been flown and continuous operating lifetimes greater than 8 years at up to 60 rpm have been demonstrated. Slip rings provide multi-channel transfer of electrical power and signals in assemblies that are small in size and weight, and low in cost. By use of multiple brushes and sufficient copper within the assembly, power transfer efficiency better than 99.95 percent for high voltage circuits can be achieved. A low slip ring failure rate based on actual space operation totalling billions of ring revolutions has been established. Well qualified suppliers who have been making slip rings for space use for over 25 years are available. It is hoped that the suspected problem in SEASAT will not be allowed to prejudice space system designer against these very useful mechanisms.

  15. Rings of Uranus as resonances with unseen satellites

    SciTech Connect

    Gorkavyi, N.N.; Fridman, A.M.

    1985-10-01

    The pattern of rings in the Uranus system is described, and previous hypothesis seeking to explain that pattern are reviewed. It is proposed that the ring pattern is produced by resonances from five undiscovered satellites located beyond the outer boundary of the rings. The satellite orbit radii would be 66,450, 62,470, 58,600, 55,380, and 51,580 km. This hypothesis is supported by the clearly nonrandom placement of the rings, enabling an accurate determination of the presumed satellite orbits. 12 references.

  16. Cassini UVIS Observations Show Active Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Esposito, L.; Colwell, J. E.; UVIS Team

    2004-12-01

    The Cassini Ultraviolet Imaging Spectrograph (UVIS) is part of the remote sensing payload of the NASA/ESA Cassini spacecraft. This spectrograph includes channels for extreme UV and far UV spectroscopic imaging, high speed photometry of stellar occultations, solar EUV occultation, and a hydrogen/deuterium absorption cell. We report our initial results from UVIS observations of Saturn's rings. Dynamic interactions between neutrals, ions, rings, moons and meteoroids produce a highly structured and time variable Saturn system Oxygen in the Saturn system dominates the magnetosphere. Observed fluctuations indicate close interactions with plasma sources. Stochastic events in the E ring may be the ultimate source. The spectral signature of water ice is seen on Phoebe and in Saturn's rings. Water ice is mixed non-uniformly with darker constituents. The high structure of the UV ring reflectance argues that collisional transport dominates ballistic transport in darkening the rings. Our preliminary results support the idea that rings are recycled fragments of moons: the current processes are more important than history and initial conditions. The spectra along the UVIS SOI radial scan indicate varying amounts of water ice. In the A ring, the ice fraction increases outward to a maximum at the outer edge. This large-scale variation is consistent with initially pure ice that has suffered meteoritic bombardment over the age of the Solar system (Cuzzi and Estrada 1998). We also see variations over scales of 1000 - 3000 km, which cannot be explained by this mechanism. Ballistic transport of spectrally neutral extrinsic pollutants from meteoroids striking the rings has a typical throw distance of 6000 km (Durisen et al 1989), too long to explain this finer structure. We propose a class of smaller renewal events, in which a small moon residing within the rings is shattered by an external impactor (Colwell and Esposito 1993, Barbara and Esposito 2002, Esposito and Colwell 2003). The

  17. Quest for the rings. In silico exploration of ring universe to identify novel bioactive heteroaromatic scaffolds.

    PubMed

    Ertl, Peter; Jelfs, Stephen; Mühlbacher, Jörg; Schuffenhauer, Ansgar; Selzer, Paul

    2006-07-27

    Bioactive molecules only contain a relatively limited number of unique ring types. To identify those ring properties and structural characteristics that are necessary for biological activity, a large virtual library of nearly 600 000 heteroaromatic scaffolds was created and characterized by calculated properties, including structural features, bioavailability descriptors, and quantum chemical parameters. A self-organizing neural network was used to cluster these scaffolds and to identify properties that best characterize bioactive ring systems. The analysis shows that bioactivity is very sparsely distributed within the scaffold property and structural space, forming only several relatively small, well-defined "bioactivity islands". Various possible applications of a large database of rings with calculated properties and bioactivity scores in the drug design and discovery process are discussed, including virtual screening, support for the design of combinatorial libraries, bioisosteric design, and scaffold hopping.

  18. Mass of Saturn's A ring

    NASA Technical Reports Server (NTRS)

    Horn, L. J.; Russell, C. T.

    1993-01-01

    The mass of Saturn's A ring is reestimated using the behavior of spiral density waves embedded in the ring. The Voyager photopolarimeter (PPS) observed the star delta-Scorpii as it was occulted by Saturn's rings during the Voyager 2 flyby of Saturn in 1981 producing a radial profile of the rings. We examined forty spiral density waves in the Voyager PPS data of the A ring including 10 weaker waves that have not been previously analyzed by means of an autoregressive power spectral technique called Burg. The strengths of this new method for ring studies are that weaker, less extended waves are easily detected and characterized. This method is also the first one which does not require precise knowledge of the resonance location and phase of the wave in order to calculate the surface mass density. Uncertainties of up to 3 km are present in the currently available radial scales for Saturn's rings.

  19. New Views of Jupiter's Rings

    NASA Astrophysics Data System (ADS)

    Burns, J. A.

    1998-09-01

    Jupiter's rings are the archetype of ethereal planetary rings (very-low optical-depth bands containing micron-sized "dust"). As a result of much improved observations by Galileo (Ockert-Bell* -- most citations are et al. and Icarus in press* or this meeting) and Keck (de Pater*), we now understand the nature of such rings. The ring has three components: a 104 km-thick toroidal halo (1.4-1.7 RJ; normal optical depth t = 10-6), a thin main ring (1.7-1.8 RJ; t = 10-6), and a pair of exterior gossamer rings (1.8-3.5RJ; t = 10-7). The main ring has patchy ( 20-30 percent) brightness. The ring is reddish and its particles satisfy a -2.5 differential power-law size distribution. Because particle lifetimes are brief, the rings must be continually regenerated, by collisions into parent bodies, which may be unseen or may be the known small ring-moons (Thomas*, Simonelli). The gossamer ring seems to be collisional ejecta derived from the ring-moons Amalthea and Thebe, and evolving inward by Poynting-Robertson drag (Burns). The particles drift through many electromagnetic resonances, clustering around synchronous orbit, which produce jumps in the particles' inclinations (Hamilton). The main ring is probably debris from Adrastea and Metis, which orbit in the equatorial plane. The halo particles are driven vertically by electromagnetic forces, which may be resonant (Schaffer & Burns) or not (Horanyi & Cravens). When halo orbits become highly distorted, particles are lost into Jupiter. Similar faint rings may be attendant to all small, close-in satellites (Showalter).

  20. The Vibration Ring. Phase 1; [Seedling Fund

    NASA Technical Reports Server (NTRS)

    Asnani, Vivake M.; Krantz, Timothy L.; Delap, Damon C.; Stringer, David B.

    2014-01-01

    The vibration ring was conceived as a driveline damping device to prevent structure-borne noise in machines. It has the appearance of a metal ring, and can be installed between any two driveline components like an ordinary mechanical spacer. Damping is achieved using a ring-shaped piezoelectric stack that is poled in the axial direction and connected to an electrical shunt circuit. Surrounding the stack is a metal structure, called the compression cage, which squeezes the stack along its poled axis when excited by radial driveline forces. The stack in turn generates electrical energy, which is either dissipated or harvested using the shunt circuit. Removing energy from the system creates a net damping effect. The vibration ring is much stiffer than traditional damping devices, which allows it to be used in a driveline without disrupting normal operation. In phase 1 of this NASA Seedling Fund project, a combination of design and analysis was used to examine the feasibility of this concept. Several designs were evaluated using solid modeling, finite element analysis, and by creating prototype hardware. Then an analytical model representing the coupled electromechanical response was formulated in closed form. The model was exercised parametrically to examine the stiffness and loss factor spectra of the vibration ring, as well as simulate its damping effect in the context of a simplified driveline model. The results of this work showed that this is a viable mechanism for driveline damping, and provided several lessons for continued development.